Python for Beginners with Hands-On Projects

[00:00] Learn Python programming from scratch [00:02] with this beginnerfriendly course with [00:04] hands-on projects. This tutorial is [00:07] perfect for absolute beginners or anyone [00:11] with zero coding experience. So, time to [00:13] learn Python programming. Sunonny Damalu [00:16] created this course. [00:17] >> Hello everyone and welcome to this [00:19] complete Python for beginners course. If [00:22] you have been struggling to learn Python [00:25] or programming in general, you have [00:28] landed in exactly the right place. This [00:31] course is designed specifically for [00:34] those who want to learn Python but have [00:37] previously found coding confusing or [00:40] difficult. Everything will be taught [00:43] step by step from level zero in a [00:46] logical and sequential order. This is a [00:49] project-based course where we will build [00:52] handson real world projects to truly [00:55] apply what you have learned. My name is [00:57] San Malu. I am a cyber security analyst [00:59] and malware reverse engineer. Welcome to [01:02] the channel. Now this is a projectbased [01:05] course. You will be able to apply your [01:08] learning through hands-on projects [01:10] because building projects or real world [01:13] applications is where the true learning [01:16] happens. In programming, we have to [01:18] bring different concepts and logic [01:20] together to build a functional [01:23] application. That's where you learn the [01:26] most. After covering the fundamentals, [01:28] we will build several projects to apply [01:31] your learning. These hands-on projects [01:34] include a password generator, MAC [01:37] address generator, a calculator, port [01:40] scanner, and password cracker among [01:43] others many projects. Okay, you can use [01:46] the timestamps provided to jump to any [01:49] specific chapter or project. So let's [01:52] not waste any time before we jump into [01:54] the code. We will cover a bit of [01:57] background on the Python language and [01:59] its uses to set the context for your [02:02] learning journey. Now if you want to [02:05] learn Python in a more structured way [02:08] with additional content and projects, [02:10] you can check out my course on Udemy. [02:13] The link is in the description. [02:18] So what is Python? Python is a highle [02:21] generalpurpose programming language. [02:24] Let's start with what a generalpurpose [02:26] language means. A generalpurpose [02:28] programming language is not restricted [02:30] or limited to a single type of task or [02:34] application. Instead, it can be used to [02:37] build a wide range of applications for [02:41] many different fields or domains. For [02:44] example, you can use Python for web [02:46] development, automation, data science, [02:48] machine learning, cyber security, [02:50] scripting, and much more. Applications [02:53] for all these domains can be created [02:56] using the same language called Python. [02:59] This is exactly why Python is the most [03:02] popular language learned by almost [03:04] everyone regardless of their [03:06] specialization in IT. No matter what [03:10] field you choose in IT, you will [03:12] eventually find yourself using Python in [03:15] some way or other. That's why Python is [03:18] called a generalpurpose programming [03:20] language. Now let's talk about what a [03:22] highle programming language means. [03:25] Python is a highle language. A highle [03:28] programming language is designed to be [03:30] human readable which makes it [03:33] significantly easier to learn and write. [03:37] It allows us to use words and structures [03:40] that closely resemble natural language, [03:43] especially English. On the other hand, [03:46] low-level languages like C and assembly [03:49] require instructions that interact more [03:52] directly with the computer's hardware. [03:55] This is what their code looks like. As [03:58] you can see, these can be quite [04:00] difficult to master at the beginning. [04:03] The syntax of these low-level languages [04:06] is much more complex and require a [04:09] deeper understanding of how a computer [04:11] works internally. Now, when we write [04:13] code in a highle language like Python, [04:16] it often feels as if we are writing in [04:19] plain English. This is what a Python [04:22] program looks like. It is simple to [04:25] write and easy to understand, right? [04:28] Highle languages do the heavy lifting [04:31] for us by automatically handling complex [04:34] tasks behind the scenes such as memory [04:36] management, hardware interaction, and [04:38] low-level system operations. This makes [04:41] development faster, reduces errors, and [04:44] allows you to focus on problem solving. [04:47] So guys, to summarize, Python is [04:49] everywhere, especially for IT [04:51] professionals. Learning Python is no [04:54] longer optional. It has become a [04:56] mandatory skill regardless of your [04:58] specialization in IT. Python will play a [05:02] role in your day-to-day work. Before we [05:05] can run or execute any Python program, [05:08] Python must be installed on our [05:10] computer. By default, a computer doesn't [05:13] understand Python code. So, the first [05:15] step is to install something called the [05:18] Python interpreter. A Python interpreter [05:20] is a program that reads and executes [05:24] Python code. When you write Python code, [05:26] the computer can't understand or execute [05:29] it directly. Computers do not understand [05:32] code written in plain English or highle [05:35] programming languages. Instead, your [05:38] code must be translated into something [05:40] called machine level instructions that [05:43] the computer can understand. This [05:45] translation is performed by the Python [05:48] interpreter. The Python interpreter [05:51] takes your Python instructions or code, [05:53] converts them into machine level [05:56] commands, then executes them on the [05:58] system. So let's install the Python. [06:01] Open any web browser of your choice. Uh [06:04] let me open Firefox [06:07] and type Python. Click on the link [06:11] python.org. [06:13] This is the exact link python.org. [06:16] And once you are here on the homepage, [06:18] click on the downloads button. Click on [06:22] it. And this is the downloading page [06:24] where we can download the Python for [06:26] different operating systems. We are [06:28] going to start with the downloading [06:30] Python for Windows. Here we have two [06:33] options for downloading Python. Download [06:36] Python installer manager or you can [06:38] download the standalone installer. We [06:41] are going to go with this standalone [06:44] installer option because it automates [06:46] your installation. So click on the [06:49] Python 3.14.3. [06:52] Click on the link and your downloading [06:54] will start right away. As you can see my [06:57] downloading has started. And if you are [07:01] on Mac OS then click on Mac OS link. [07:05] Click on it. Scroll down a little. And [07:08] this is the latest version of Python. So [07:12] here we have the download link. Click on [07:14] the Mac OS installer link and your [07:17] downloading will start right away. It [07:20] will download the file withpkg or [07:23] package extension. Now once the [07:26] downloading is complete now we can [07:28] proceed with the Python installation. We [07:31] are going to start by installing Python [07:33] on Windows. So go to the folder where [07:37] you have downloaded your Python file. [07:40] Now double click on the Python file that [07:43] you just downloaded. Now here it is an [07:46] extremely important point. We need to [07:49] check this button add Python.exe [07:53] to path. Click or check on this button. [07:56] It will basically make your Python [07:58] accessible from anywhere in the [08:00] terminal. So check this button. Add [08:02] Python.exe ext path. Now double click on [08:06] the install now option and your download [08:10] sorry your installation uh process will [08:14] start right away. [08:17] All right guys, as you can see setup was [08:20] success successful. Now click on the [08:22] close button to close this window. Now [08:24] let's uh actually verify whether we have [08:28] installed Python successfully or not. So [08:31] what you are going to do is open the [08:33] PowerShell. Press Windows key. Type [08:36] PowerShell. So click on the PowerShell [08:38] icon. You will see either PowerShell 7 [08:41] or PowerShell 5. So click on whatever [08:44] appears the first. I'm going to click on [08:46] PowerShell 7. [08:49] Now type py press enter. As you can see [08:54] guys, we have successfully installed the [08:57] Python. So as soon as I pressed enter, [08:59] now I'm inside the Python's console. [09:02] Here I can uh write Python code [09:08] print [09:11] hello. [09:13] So we have successfully installed the [09:15] Python. Now to exit out of the Python's [09:19] console, press control + D together. Now [09:22] we are out of the Python's console or [09:25] you can simply type Python. It will also [09:28] press enter. It will also take you to [09:30] the Python's console. Let's check the [09:34] current version of Python that we have [09:35] downloaded. So Python [09:40] version we need to add two hyphens like [09:43] this. So here we have the current [09:47] version of Python which is 3.14.3. [09:50] So guys, we have successfully installed [09:52] the Python on Windows. In this video, we [09:55] will install the Z code editor. A code [09:57] editor is a workplace where you write, [10:00] modify, and view your programs or code. [10:04] There are many excellent code editors [10:06] available, but we are going to use the [10:09] Zed code editor. Zed is a new next [10:12] generation modern code editor that is [10:14] smooth, fast, and extremely lightweight. [10:18] It doesn't consume excessive system [10:20] resources such as RAM or CPU like other [10:24] major code editor VS code. Just like [10:28] other good code editors, Zed provides [10:30] helpful features such as syntax [10:33] highlighting, autocomp completion, [10:34] formatting tools, etc. which makes the [10:37] writing code easier, faster, and more [10:40] efficient. The reason I'm choosing Zed [10:42] over VS Code is that it is lightweight [10:45] and uses minimal system resources such [10:49] as RAM and CPU. This means there won't [10:52] be slowdowns or lags even on the low-end [10:56] systems. It is best choice for [10:58] beginners. Now the popular code editor [11:00] like VS Code, it is powerful but it is [11:03] quite heavy and consume a lot of RAM and [11:06] CPU even for standard tasks. That's why [11:09] zed is an absolutely outstanding [11:12] alternative. I have completely switched [11:15] from VS Code to Zed. It has everything [11:18] you need in a modern code editor. Plus, [11:21] it is faster than all other major code [11:25] editors. Now, let's dive into the [11:27] practicals. Open any web browser and [11:31] type uh zed code editor. Click on the [11:35] link zed.dev. deev. [11:38] Again, this is the exact link or address [11:41] z.dev. Once you are here in the [11:43] homepage, you can click on the download [11:45] button button that is uh appearing in [11:48] the in the menu bar here or you can also [11:50] click on the download button uh here. [11:53] So, click on the download now. Now, here [11:56] we can download the Z code editor for [11:58] different operating systems. Let's [12:01] download the Z for Windows. Here we have [12:04] the downloading option for Windows. [12:06] Click on the download now button. Your [12:09] downloading will start right away. As [12:11] you can see, mine has already started. [12:14] Now, let's download the Z code editor [12:17] for the Mac OS. So, let me go back to [12:20] the Mac uh the download page. Now the Z [12:23] code editor is available for both Intel [12:27] based Apple computers as well as the the [12:30] latest Apple computers that use uh Apple [12:35] silicon chips like M1, M2, M3 etc. [12:38] Right? So click on this down arrow. If [12:41] you have Apple computer with Apple [12:43] silicon chips like M1, M2, then click on [12:46] this option and click on download. Now [12:48] your downloading will start right away. [12:50] If you have an old Apple computer with [12:54] the Intel chip or Intel processor, then [12:57] click on Intel chip and click on [13:01] download. Now your downloading will [13:03] start right away. As you can see, once [13:06] the installation is complete, we are [13:08] good to go. Let's install the Z code [13:12] editor on Windows first. Now, double [13:15] click on the Z code editor file that you [13:18] just downloaded. Double click on it. And [13:22] here we need to agree term terms of [13:24] service. Click on I accept the [13:26] agreements. Click on next. This is the [13:30] installation path where your Z code [13:32] editor will be installed. Click on next. [13:35] And I'm going to check this button [13:37] create a desk desktop icon so it is [13:40] easier to access. Now click on uh next. [13:44] And the download uh sorry the [13:46] installation has started. It will take [13:48] probably a minute or two to get the [13:51] installation done. So wait patiently. [13:56] As you can see guys, the installation is [13:58] complete. Now here as you can see we [14:00] have this button launch zed. It is [14:03] already being checked. So if I click on [14:05] finish, it will it will launch or start [14:07] the the Z code editor. So click on [14:10] finish. [14:12] It has started the Z code editor. And [14:15] for some reasons if your code editor [14:17] doesn't start then you can open it [14:20] manually. Press uh Windows key type zed [14:24] and here you will see this zed code [14:27] editors icon. Click on it. Then your zed [14:31] editor should start. This is the welcome [14:33] window. Now this window only appears [14:36] when you open the zed code editor for [14:38] the first time. Here we need to select [14:40] the theme that you want to use for the [14:44] the Z code editor. So what I'm going to [14:46] do is I'm going to go with the dark [14:48] theme because all the programmers uh [14:51] prefer or majority of programmers prefer [14:54] the dark theme. So click on the dark tab [14:57] as you can see. Now click on the finish [15:00] setup. So guys we have successfully [15:03] installed the Z code editor. So I'm [15:07] going to leave it here. In this video, [15:09] we are going to configure and optimize [15:11] the Z code editor. We will make a few [15:14] changes and set it up correctly so we [15:17] can start writing our programs [15:19] efficiently. Let's dive into the [15:22] practicals. So open your uh Z code [15:25] editor. [15:27] Now when you will open the Z code [15:29] editor, you will see a window similar to [15:32] this. Just click on new file and uh let [15:37] me write some dummy code. Print [15:42] hello there. Now first thing that I'm [15:45] going to do is uh change the font size. [15:48] As you can see this font size might not [15:51] be you know large enough for for the [15:54] most users or programmers. So let's uh [15:57] uh increase the font size. uh at the [16:00] left top click on the click on this menu [16:04] and uh from here click on open settings. [16:09] Now here click on the appearance tab and [16:12] scroll down. [16:14] As you can see guys here you can [16:15] customize the font size. [16:19] Click on the plus button to increase the [16:21] font size. Okay, I'm going to keep it 18 [16:26] or 19. As you can see, as you click on [16:28] the button or increase the font size, [16:31] the it gets updated inside your code [16:34] editor. I'm going to keep it 18. It it [16:37] is good enough for me. So, yeah, that's [16:40] it for uh this window. Click close this [16:43] window. Now, next thing that I'm going [16:45] to do is change its appearance. The [16:48] Zcode editor has uh as many built-in [16:52] themes that you can that you can, you [16:54] know, choose from. Again click on the [16:56] menu. [16:57] Click on select theme option and these [17:01] are the themes that you can choose from. [17:04] This is the default one dark. You can uh [17:07] try all these different themes. So let's [17:09] click on this first theme. Are you dark? [17:13] Now we have a different appearance. Uh [17:16] again let's uh open the themes menu. [17:18] Select themes [17:20] and uh let's go for iod dark. So guys [17:24] you you can you can you know experiment [17:26] around and choose the appropriate theme [17:29] that suits your style. You can use [17:31] shortcut for opening themes menu. Press [17:34] control + K then press control + T. It [17:38] will it will bring up the themes menu. [17:41] I'm going to uh select the one dark. [17:45] Now let's see how we can install [17:48] extensions. Extensions are basically [17:50] add-on that expand the editor's [17:53] functionality similar to plugins in [17:55] other code editors like VS Code. By [17:57] default, a text editor comes with core [18:00] features that are sufficient for basic [18:03] coding. However, if you need additional [18:05] support or more features to streamline [18:08] your workflow, you can install specific [18:10] extensions to meet those needs. For [18:13] example, you can in install new themes [18:16] to change the visual look and feel of [18:19] your editor. Even though the editor [18:22] comes with several built-in themes, as [18:24] we have seen, you can always install [18:26] additional themes to create a better [18:29] experience that suits your personal [18:31] style and workspace. So, what I'm going [18:34] to do is install an extremely popular [18:36] theme called called One Dark Pro. So [18:41] click on the menu and click on down here [18:45] we have extensions. Click on it. Here [18:48] you can you know search for the [18:50] extensions that you want. On the right [18:54] side if you click on uh installed uh [18:57] then it will it will display the [18:59] extensions that you have installed. It [19:02] already has HTML extension installed [19:04] which is the default extension which is [19:07] part of the core uh installation [19:09] package. Now click on the all and click [19:12] on the search extension box. Now I'm [19:14] going to search for one dark [19:18] pro. As you can see here we have one [19:20] dark pro and uh it has already been [19:23] downloaded by almost 200,000 people as [19:25] you can see. Now click on the install [19:27] button. It will install the theme in a [19:30] few in few seconds. As you can see guys, [19:32] it is already installed. Okay. Click on [19:36] one dark pro. [19:40] Now back to the code editor. As you can [19:42] see guys, now we have a different [19:44] appearance. Let me open the open the [19:48] themes menu. Presst controll + k [19:51] thentroll + t. From here select the one [19:54] dark pro. Click on it. As you can see [19:56] now we have a much better appearance. [19:58] This is the theme that I personally [20:00] like. I have been using this for like 3 [20:03] years now. [20:06] And if you want to uninstall an [20:09] extension then click on the installed [20:12] and here you will see the uninstall [20:16] option uh button. Click on it then it [20:18] will uninstall the selected extension. [20:21] So after installing an extension it is [20:23] always recommended to restart your code [20:27] editor. So I'm going to close it [20:30] and let start it again. new file. [20:34] Similarly, you can install extensions [20:37] for various purposes such as syntax [20:39] highlighting. For example, if you want [20:41] to write code in PowerShell, then you [20:44] should then you know we can install the [20:46] extension called PowerShell. This will [20:49] provide you with essential features like [20:51] autocomp completion syntax highlighting, [20:54] error detection, error detection, etc. [20:58] Right? [21:00] So here just search for the extension [21:03] let's say powershell then you know all [21:05] the matching options will appear here [21:08] then you can install the appropriate [21:10] option. So guys this is basically the [21:12] vast marketplace where you can view [21:15] browse and install and manage your [21:18] extensions. Now that we have [21:20] successfully set up Python and our code [21:23] editor it's time to write and execute [21:26] our first Python program. So in this [21:29] lesson we are going to create our first [21:31] Python file, run it, check the output [21:34] and learn about the print function. Now [21:37] let's dive into the practicals. So open [21:40] your Z code editor. If you have a [21:43] different interface than this, do not [21:45] worry. We are going to start from the [21:47] scratch. Now on the left top, click on [21:51] this applications menu. Click on it. Now [21:55] go to the file. Click on new. We are [21:57] going to create a new file. So here let [22:01] me write a simple print statement [22:05] hello world. Do not worry about this [22:08] print function that I have just written. [22:10] It will be explained later in the video [22:13] in detail. For now write exactly as it [22:17] is. Print then within the parenthesis [22:20] and quotes write the hello world exactly [22:23] as I have written. Now we need to save [22:26] this file. Press Ctrl + S to save. Now [22:30] what I'm going to do is create a [22:31] dedicated folder where I will save all [22:34] my Python files. So let me save create [22:39] Python directory. [22:41] Double click on it. This way it will be [22:44] easier for me to manage and access all [22:47] my Python files. [22:50] Now give a name to your uh Python file. [22:53] Hello. Py. Now the do.py extension is [22:57] extremely important. A Python file [22:59] always ends with py extension. And of [23:03] course you can give any name to your [23:06] Python file but the extension must [23:09] always be pi. Now click on save. Okay. [23:13] We have successfully created and saved [23:16] our first Python file. As you can see we [23:20] have the syntax highlighting as well. So [23:22] when you save a file, the Z code editor [23:25] enables the syntax highlighting [23:28] automatically. Now next step is to run [23:31] and execute our Python file. To execute [23:35] uh our Python code, we are going to need [23:37] to open our terminal. Fortunately, the Z [23:41] code editor provides the integrated [23:44] terminal. We don't need to open a [23:47] dedicated terminal window. On the right [23:50] bottom we have the terminals uh icon. [23:54] Click on it. As you can see guys it has [23:57] opened the PowerShell. By default the Z [24:01] code editor works with PowerShell. This [24:03] is the current version of PowerShell. [24:05] And if you see PowerShell uh version [24:08] five then then also it doesn't matter. [24:12] Your code will run regardless. Now I'm [24:15] going to stack my my PowerShell on my [24:18] right side. Again go to the terminals [24:22] icon at the right bottom. Right click on [24:26] it. Click on dock right. As you can see [24:29] we have successfully docked or stacked [24:32] our terminal on the right side. Let me [24:35] run the clear command. Now to execute a [24:39] Python file, we need to launch or start [24:42] the Python's interpreter. So write py as [24:45] we already know the pi or python command [24:49] they start the python interpreter. So if [24:51] I press enter, as you can see, we are [24:53] inside the python's console. However, we [24:56] are not going to go inside the python's [24:58] console. we will instead provide a file [25:01] name to to the Python's interpreter so [25:04] it can execute the code inside that [25:06] file. So press control + D to exit out [25:10] of the Python's console. Let me clear [25:13] the terminal. Now write pi. If you are [25:17] on Mac OS then type Python 3 like this. [25:22] Okay. If you are on Windows just type [25:25] pi. Now space. Now we need to tell the [25:29] Python the exact file name that you want [25:33] to run or execute. So after space we [25:37] need to provide either the file name or [25:40] the full path to the file where your [25:42] file is saved or stored. My file is [25:46] stored. Let me go to the directory where [25:48] I have stored my file. I just want to [25:51] copy the full path. So inside the python [25:55] uh directory I have this python file. So [25:58] uh click on anywhere in your blank [26:00] space. Now press alt + d. As you can see [26:04] this is my path. Now we need to copy [26:07] this path. Press control + c. [26:11] Now within quotes paste your path. Let [26:15] me paste it back slash. Now inside my [26:18] python directory as you can see I have [26:21] this file called hello.py. So write the [26:23] exact file name hello.py. [26:27] I will show you an easier way to copy [26:29] the path in a minute. For now we are [26:32] doing it manually. [26:34] So here I'm telling my Python that uh go [26:37] to this location d/python. In this [26:41] directory I have this file called [26:43] hello.py run and execute this file. So [26:46] press enter. As you can see we have the [26:49] hello world being printed. We have [26:51] successfully executed our hello.py file [26:55] which is stored or saved at this [26:58] location. Now the easiest way to to copy [27:01] a file path is simply right click on [27:05] your files tab like this. Right click on [27:08] it. Now copy the path. [27:11] Let me clear the terminal. [27:15] Now press up arrow key to bring up the [27:18] previously executed commands like this. [27:22] Now within quotes [27:26] let me paste the path. As you can see we [27:30] have successfully copied and pasted the [27:32] file path where it is stored. Press [27:36] enter. As you can see we have executed [27:38] our file. Now let me explain this print [27:42] function what it does. The print [27:44] function as the name suggests it prints [27:48] or displays the output in the terminal. [27:51] When you create real world applications, [27:54] we always need to print or display [27:58] information to the user when they run [28:01] your program. Right? That information [28:04] can be anything. It can be a simple [28:06] message like this. Hello world or [28:11] output or result of a calculation like [28:14] this [28:18] as you can see. So if you want to print [28:20] or display anything uh in the terminal [28:23] then we use the print function. We just [28:26] have to tell the print function what you [28:28] want to print. Here at line number one, [28:30] I'm telling print function that print [28:33] this hello world in the terminal. So it [28:35] printed the hello world. At line number [28:38] two, uh I'm telling Python to calculate [28:41] these two numbers then print the result [28:44] in the terminal. So it exactly did this. [28:46] So if you want to print anything then [28:49] write that within the parenthesis of [28:52] print function like this then it will [28:54] print or display that in the terminal. [28:56] So that's how you can create and execute [28:59] your Python uh Python programs. Now [29:02] before signing off, there is one one [29:04] more thing that you need to know about [29:07] uh executing your Python code. When you [29:10] provide path to your Python file like [29:13] this, always surround your path within [29:16] quotes like this. If you do not provide [29:20] within quotes, then it can create [29:22] problems in certain situations. For [29:25] example, if let's say your folder name [29:28] is something like this Python code, then [29:31] uh Python will throw an error. It will [29:34] treat these two words as separate [29:38] directories or folders. [29:41] But when you put it within quotes, then [29:44] it will treat it as a single folder. So [29:47] that's why you should always surround [29:48] your path within the quotes like this. [29:52] So that's it for this video guys. In [29:54] this video we will take a deeper look [29:56] into the print function. We will learn [30:00] some core uh concepts such as string [30:03] statements and how to print uh text in [30:07] multiple lines. Now let's dive into the [30:10] practicals. Let me write a simple print [30:13] function. Hello. [30:15] Hello world. Let's execute the code. [30:18] Okay, we have successfully printed hello [30:20] world. So we are going to start with [30:22] with the string. What a string is a [30:25] string is nothing but the technical name [30:29] for text in programming. So this is a [30:32] string right? Even though you can call [30:34] it text but in programming we call text [30:38] string. So this is basically a string. [30:41] Now one thing that you need to know [30:44] about [30:45] uh text or string is that a string is [30:49] always stored or written within quotes [30:54] like this. [30:56] I am learning [30:59] Python. Okay. [31:04] Now let's write a mathematical [31:06] expression. [31:08] Let's execute the code. we have uh 2 0 [31:11] which is uh result of 12 + 8. Now Python [31:17] is treating it as a mathematical [31:19] expression. However, if I put the same [31:22] mathematical expression within [31:25] a quote then it becomes a string. So [31:29] like I like I was saying if you put [31:32] anything within single or double quotes [31:34] in Python that becomes a string. Let's [31:36] execute the code. This time Python did [31:39] not calculate these two numbers rather [31:43] it printed them as they are along with [31:45] the the plus right because when you put [31:48] anything within quotes Python treats [31:50] that as a string. So here Python is [31:53] assuming that okay since you have [31:56] written it within quotes it uh it is a [31:59] string you just want to print these [32:01] characters. Now if I remove the [32:06] quotes then yeah Python is going to [32:09] treat them as numbers or as mathematical [32:13] expression. So guys that's the most [32:15] important thing about a string in [32:17] Python. A string is nothing but the [32:20] technical name for text and a string is [32:24] always written within quotes. If you put [32:27] anything within a code whether uh [32:30] letters or numbers, Python treats that [32:32] as as a string. Okay. Now let's move on [32:36] to the statement. [32:38] Now a statement in programming is [32:40] nothing but an instruction that we give [32:43] to our program. Here I'm giving these [32:46] three instructions. Right? Here I'm [32:48] telling Python, okay, print hello world. [32:50] So it is printing it. Here I'm telling [32:52] print 12 + 8. I'm basically asking [32:55] Python to give me out result of 12 + 8. [32:58] So it is exactly doing this. So [33:00] statements can be simple lines like this [33:03] or complex instructions like you know [33:06] if statement like this. This is also [33:10] also a statement. Here I'm instructing [33:12] Python to compare these two numbers. [33:15] Right? I hope the statements are clear. [33:19] Now now let's see how we can utilize [33:22] multi- lines. Okay. Let's say you have a [33:24] paragraph that spans multiple lines. [33:27] Hello world. [33:32] Now here we have a paragraph that is [33:35] spanning multiple lines. Right? But if I [33:39] attempt to execute this code, I have an [33:43] error here. Print syntax unterminated [33:45] string literal. In Python, you can't [33:48] break or split a string into multiple [33:51] lines like this inside the print [33:53] function. Python expects a string [33:56] starting with the quote to end in the [33:58] same line. Okay? When it doesn't see the [34:00] closing quote before the line ends, it [34:03] stops or throws an error like this. Now, [34:07] this can be fixed using three quotes or [34:10] triple quotes like this. 1 2 3 at the [34:13] beginning. Now, we need to close these [34:15] three quotes here. [34:18] Now, it will fix the error as you can [34:22] see. [34:29] So here we are using three opening [34:31] quotes. So Python is going to check for [34:34] the three exact closing quotes uh for [34:37] the termination. Okay. So if you want to [34:41] write a paragraph that spans multiple [34:43] lines then always use three opening and [34:46] closing quotes. Then you know you can [34:48] write as many lines as as as you like. [34:52] it doesn't matter. [34:54] So that's the print function. In this [34:57] video, we will take a look at escape [35:00] sequences in Python and how they are [35:02] used in strings. Uh they are primarily [35:05] used to format the output of your code [35:08] such as inserting new lines, creating [35:11] tab spaces, or displaying characters [35:13] that usually have reserved meaning. An [35:16] escape sequence always starts with a [35:19] backslash and is used to represent [35:22] characters that are difficult or [35:24] impossible to type directly in a string. [35:27] It escapes the normal interpretation of [35:30] the string to perform a specific [35:33] function or action. Now let's dive into [35:35] the practicals. We are going to start by [35:38] creating a new line. So let's print [35:42] hello [35:44] world I am learning [35:49] Python right let's execute the code [35:54] and we have the expected result now [35:58] I want to print this portion of this [36:01] string in a new line right we have two [36:04] options uh to achieve this either we can [36:07] take this portion of the string and put [36:09] it inside a new print function then it [36:13] will be printed in a new line. Right? [36:15] However, this is not efficient. Right? [36:18] Here we are writing a dedicated print [36:21] function just to have a new line or [36:23] print it in the new line. Now there is a [36:28] better and efficient way to get the same [36:30] thing done. Let's put it back inside the [36:33] print function. We can use the escape [36:36] sequence. An escape sequence is a [36:39] combination of two or more characters. [36:41] An escape sequence always starts with [36:44] backslash followed by a specific [36:47] character n. Now this combination [36:50] creates a new line. Let's execute the [36:52] code. As you can see guys, line after it [36:55] has been printed in a new line. So [36:57] anything that you write after this [37:00] combination back slashn that will be [37:02] printed or displayed in a new line. An [37:06] escape sequence always starts with [37:08] backslash because that's how Python [37:11] differentiates escape sequences from [37:13] ordinary text inside a string. So it [37:17] basically tells computers that do not [37:20] treat next character or this combination [37:23] as a regular text or string. Right? [37:26] Treat it as a special command. So this [37:29] special command has the meaning that [37:32] creates a new line. Okay. Another [37:37] popular escape sequence is [37:40] t /ash t is for tab. It creates four [37:45] spaces. Press enter. As you can see / t [37:49] tab it creates four spaces. So these two [37:53] are very popular escape sequences that [37:56] uh that you know we use in most programs [37:59] specifically this backslash n it creates [38:02] a new line. Now let's try it uh try back [38:06] slash i. Now this is not a valid escape [38:10] sequence or valid combination. Right? [38:12] There are only certain escape sequences [38:14] or combinations that have special [38:16] meaning like backlash n. Not every [38:19] character that follows a backslash has a [38:22] special meaning. So when Python [38:24] encounters backslash n or any valid [38:28] combination in a string, it interprets [38:30] that accordingly. So that's it for this [38:33] video guys. In this quick video, we are [38:35] going to learn how to create and add [38:37] comments in Python. Comments in code are [38:40] notes that we write to explain what the [38:43] code does. They are used to describe the [38:46] purpose and logic of the code. Python [38:49] ignores comments during execution, but [38:51] they make programs easier to understand, [38:54] debug, and maintain. Now, let's dive [38:57] into the practicals. Let me write a [38:59] simple print function. Hello world. [39:03] Let's execute it. And we have the [39:06] expected hello world being printed. Now, [39:09] let's add a comment. A comment always [39:12] starts with the hash or pound sign like [39:16] this. So I'm going to add the commentary [39:20] the below [39:22] print function [39:24] print function [39:27] prints [39:30] hello world. [39:34] Now let's execute the code [39:37] and we have the same output. If you [39:40] notice guys, even though we have added [39:41] this comment, Python did not execute uh [39:44] this line or line number one because it [39:47] is a comment. So when a line starts with [39:50] the pound or hash, Python completely [39:53] ignores that line. It automatically [39:56] understands that this is a comment. This [39:59] is not for me to execute. A comment [40:02] helps uh people to understand the code [40:05] or the specific section of the code [40:08] where you have written the comment. Now [40:11] see guys, comments are necessary when [40:13] you are working with a team. When [40:16] someone else sees your code, without [40:18] comments, it is very difficult to [40:21] understand what your code is doing. Now [40:24] here it is pretty obvious that this [40:26] print function uh is printing hello [40:28] world. But when your code has complex [40:31] logic then comments are necessary. You [40:34] have to write the comments what that [40:37] particular section of the code is doing. [40:40] Even if you revisit your code after [40:43] let's say a week or 10 days then you are [40:46] going to need the comments. Otherwise it [40:49] will take you some time to understand [40:51] your own code. Now the comments can be [40:54] added anywhere. You can also write [40:56] comment like this. [40:58] It prints hello. It prints hello. [41:02] Hello world. It doesn't matter where you [41:05] write the comment as long as it starts [41:08] with pound. So first character of a [41:10] comment is always the pound. That's how [41:14] Python recognizes a comment. Now [41:17] comments can also be used to disable [41:21] uh the code or lines of codes like this. [41:23] Let's see here. I'm printing this and we [41:27] should have 102 in the output as you can [41:30] see. Now I want to disable this line [41:33] temporarily. So what I'm going to do is [41:36] add pound sign at the beginning. As you [41:39] can see now the line number four hasn't [41:42] been executed. Right? We only have hello [41:45] world. This is because this line starts [41:47] with pound. So when anything starts with [41:51] the pound, Python will not execute that [41:54] particular line. Whether that line is a [41:58] legitimate Python statement like print [42:01] or a comment like this, it doesn't [42:03] matter. Python simply ignores that line. [42:06] So you can use the uh the bound sign to [42:10] ignore [42:13] uh ignore or disable the [42:15] code lines like this. [42:18] So that's it for this video guys. [42:21] Before creating variables practically [42:24] let me explain what a variable is for [42:27] absolute beginners. In simple terms a [42:29] variable is a container that stores [42:32] data. This data can be anything such as [42:35] a number text or a file name. Once [42:39] stored in a variable the data can be [42:41] accessed, used and reused anywhere in [42:45] the program. Variables solve two major [42:47] problems in programming. Data storage [42:50] and data reusability. Let's start with [42:53] data storage. Suppose you are creating a [42:55] banking application. Bank account [42:58] numbers are often lengthy, right? [43:00] Usually 10 to 16 digits long, right? [43:04] Now, if you need to use the same account [43:07] number multiple times in a program, [43:10] manually typing or remembering such a [43:13] long number is difficult. errorprone and [43:16] impractical. Now to solve this problem, [43:18] you can store the account number in a [43:21] variable. Once it is saved, you only [43:24] need to use the variable's name to [43:27] access the number. Referring to the [43:29] variable instead of typing the number [43:32] manually eliminates mistakes and makes [43:34] the program much easier to manage. The [43:38] best part about variables is [43:40] reusability. Once a variable is created, [43:43] a variable's value can be accessed as [43:46] many times as needed simply by using its [43:49] name. Now let's dive into the [43:51] practicals. I'm going to create a [43:54] variable that stores a bank account [43:57] number. So account number ACC equal to [44:00] let's assign it a random long value. We [44:03] have successfully created the variable [44:07] ACC. This is the variable name. And of [44:10] course you can give any name to your [44:13] variable. Then we have this equal to [44:16] sign. Equal to sign in programming is [44:18] also known as the assignment operator. [44:22] The assignment operator assigns data or [44:25] value to a variable. So here I'm telling [44:28] Python that take this value or data and [44:33] assign [44:35] uh or store it in the ACC variable. As [44:38] soon as you assign data to a variable, [44:41] that variable gets created in Python. So [44:46] this ACC variable is storing or holding [44:48] this data. And if you want to use this [44:52] data anywhere in your program, then all [44:56] you have to do is refer to the ACC [44:59] variable name. Then you will be able to [45:02] access this data. Now that we have [45:05] created a variable, let's see how we can [45:07] access variables in Python. I'm going to [45:10] print the value assigned to the ACC [45:13] variable. So write the exact variable [45:16] name. The print function is going to [45:18] display the value stored in the ACC [45:21] variable. Let me save the code. You will [45:23] see a difference when I save the code. [45:27] As you can see, as soon as I saved the [45:30] code, the Z code editor automatically [45:34] created or added spaces on both sides of [45:37] the equal to sign or assignment [45:40] operator. Well, this is not mandatory. [45:44] The Z code editor does this for the code [45:48] formatting. This way, the code looks [45:50] clean, right? This is also a perfectly [45:54] valid way to assign value to a variable. [45:58] Now let's uh execute the script. As you [46:01] can see, we have successfully accessed [46:03] the ACC variable or data assigned to the [46:06] ACC variable. Right? So guys, that's how [46:09] you can create and access variables in [46:11] Python. Now one thing that you need to [46:15] be careful about when accessing [46:18] variables is never put uh your variable [46:22] within single or double quotes when [46:24] accessing them. So if you like this so [46:27] if you put variable within quotes then [46:31] Python will not treat them as variables. [46:35] Let's execute the code. This time the [46:38] print function has printed ACC as it is. [46:41] This is because when you put anything uh [46:45] within quotes in Python, Python treats [46:49] that as a string. Here the print [46:52] function is assuming that this ACC is a [46:55] string that you want to print or display [46:59] in the terminal. It is not recognizing [47:02] it as a variable. So to access [47:05] variables, never put them within quotes. [47:08] Now it will print the value assigned to [47:10] the ACC variable as you can see. Now [47:14] let's uh create a few more variables for [47:17] a better clarity. ID equal to 1,000 [47:21] name equal to let's say root. Here we [47:24] have a very visible difference, right? I [47:27] have surrounded the text or string value [47:31] within quotes, not the numbers. Well, [47:34] you always have to surround the text or [47:39] string value within quotes in Python. If [47:42] you don't, then it will throw an error [47:45] as you can see. So, always surround the [47:49] string value within within single or [47:52] double quotes when assigning it to a [47:54] variable in Python. And never surround [47:58] your your numbers within quotes because [48:00] if you surround your numbers within [48:03] quotes then Python will treat those [48:06] numbers or values as string. Now let's [48:10] access these two values as well ACC, [48:15] ID. Now comma is extremely important [48:19] when accessing variables inside the [48:22] print function. we need to separate the [48:25] variables with commas. Commas basically [48:29] display the different variables or [48:31] different pieces of information in a [48:34] single line of output. So let's access [48:37] name as well. Let me save the code. As [48:40] as you can see here also the Z code [48:43] editor has added spaces. This is also a [48:47] perfectly valid way to separate [48:49] variables inside the print function. [48:52] Let's access uh sorry run the program. [48:55] As you can see we have successfully [48:58] accessed values assigned to these three [49:01] variables. Now let's format this a [49:03] little [49:06] account equal to. Now we also need to [49:11] separate this string from variable using [49:14] comma like this. [49:18] ID equal to ID again comma [49:23] name equal to name variable [49:28] and we have the expected output. That's [49:31] how you can create and access variables. [49:35] Now one thing that I emphasized a lot [49:38] earlier in the video is uh that [49:40] variables are reusable. [49:43] Reusable simply means once you create a [49:46] variable then you can access that [49:49] variable as many times as you need in [49:51] your program. So let's uh access the [49:56] name variable. [49:58] As you can see we have successfully [50:00] accessed the name variable twice. [50:04] Similarly, you can access [50:06] the name variable or any other variable [50:10] as many times as you like. Just write [50:14] the exact variable name. Like this, we [50:17] have and now we have accessed the name [50:21] variable thrice. Now, there are certain [50:25] rules that you need to obey or follow [50:28] when creating variables. So what I'm [50:31] going to do is get rid of uh most of the [50:34] stuff in my program. The rule number one [50:37] for creating variables in Python is a [50:40] variable name can't start with a number. [50:44] For example, one ACC. This is not a [50:46] valid variable. [50:50] As you can see, we have uh an error here [50:53] because a variable name can never start [50:56] with a number. Your variable uh names [51:00] can have numbers uh just not at the [51:03] beginning. You can include numbers at [51:06] the end or middle like this. Account [51:08] number one. This is a valid variable as [51:11] you can see. Now a variable can only [51:16] have one special character. That special [51:19] character is underscore acccc_1. [51:22] This is a valid variable name in Python [51:26] as you can see. [51:29] Now other special characters are not [51:32] allowed in the variable names like uh at [51:36] the rate dollar sign. These are not [51:39] allowed in a variable. The only special [51:41] character allowed in variables is [51:44] underscore. Python is a case sensitive [51:46] language. It means it treats lower case [51:50] and uppercase characters differently. [51:52] For example, ACC and ACC in uppercase. [51:56] Now these two are valid variables and at [52:00] the same time they are different [52:02] variables even though we are using the [52:05] same letters for for the names since the [52:09] second variable is in uppercase letters [52:12] Python is going to treat it as a [52:15] separate or different variable. So let's [52:19] execute [52:20] uh sorry let's access the second [52:23] variable ACC. [52:26] As you can see we have accessed both the [52:29] variables. The topic for this video is [52:32] primary or fundamental data types. In [52:34] programming a data type is a very [52:37] important concept. As we have seen [52:39] variables can store data of different [52:41] types. Data exists in many forms. For [52:45] example, 45 is an integer data type. [52:48] 23.5 is a float or decimal data type. [52:52] Root is a string data type. These are [52:54] primary data types. We can create [52:56] variables to store different types of [52:59] data. And each variable can hold a [53:02] different value depending on its type. [53:05] This allows us to store any kind of data [53:08] in a a Python variable. Python has many [53:12] built-in data types available by [53:14] default. We will cover each of them as [53:17] we progress through the course because [53:20] explaining them all in a single video is [53:22] not practical and helpful at this stage. [53:26] Some of more advanced secondary data [53:29] types require understanding of a few [53:32] basic concepts first. So for now let's [53:35] focus on the essential primary data [53:37] types that we we use on a daily basis. [53:41] Uh I'm going to create uh multiple [53:44] variables and assign different types of [53:46] data uh to them. A equal to [53:50] 78 [53:52] name equal to [53:55] root [53:56] salary equal to a decimal number. [54:00] Now here we have three different [54:02] variables right? A name and salary and [54:05] all these variables are storing [54:07] different values. A it is storing an [54:11] integer as you can see name it is [54:14] storing a string and the salary it is [54:17] storing a completely different data that [54:21] is a decimal number. This way guys, you [54:24] can basically assign any type of data to [54:29] a variable, right? You don't need to [54:32] explicitly tell Python the type of data [54:36] that you are assigning to a variable. [54:38] Python automatically figures that out in [54:41] the background and allocates the [54:43] appropriate memory space for them. So as [54:46] soon as you assign uh data to a variable [54:49] in Python, that variable gets created, [54:53] right? You don't have to worry about the [54:56] type of data you are assigning to a [54:58] variable. [55:00] Now we have a type function in Python [55:04] that basically tells us the type of data [55:06] that is being assigned to a variable. So [55:10] type inside the parenthesis specify the [55:12] variable name or a value. Let's execute [55:16] the code. As you can see, it is telling [55:18] int class int. int means this a variable [55:22] is storing an integer value. [55:27] Print [55:28] type [55:31] name. [55:33] Now as you can see string the name [55:36] variable is storing a string value. [55:39] Similarly, [55:44] and the salary variable is storing a [55:48] load or decimal number. Now, float in [55:51] Python basically represents a decimal [55:54] number. Now, these are basically called [55:57] the primary data types in Python that we [56:01] use almost in all our programs. And now [56:05] these are just the very basic data types [56:08] in Python. Python have has many more [56:12] data types. Uh we have secondary data [56:15] types like uh uh like uh list, [56:20] tuple, sets [56:23] a and many more. We also have the [56:25] boolean data types. We will cover all [56:29] these different data types as we [56:31] progress uh in the course. Okay, so [56:34] that's pretty much it for this video. In [56:38] this video, we will explore string [56:40] functions in Python, more accurately [56:42] known as string methods. Python provides [56:45] a wide range of built-in methods that [56:49] let us efficiently manipulate and [56:51] analyze strings. These methods are [56:54] absolutely essential for text processing [56:56] and output formatting. For example, [56:59] using built-in methods, we can find [57:02] length of a string, convert uh text to [57:05] uppercase or lowerase, slice, trim or [57:08] modify strings, and much more. Let's [57:10] jump into the practicals. Let me create [57:13] a variable and assign it a string value [57:16] because we are going to manipulate [57:18] strings. Uh let's say root admin user. [57:23] Now first thing that I want to do is [57:27] check length of this string. Length. [57:30] Checking length simply means counting [57:32] how many characters are uh in a string. [57:37] So print the function for checking [57:40] length of a string is length len [57:44] parenthesis. Inside the parenthesis we [57:47] need to provide either a string or a [57:50] variable name. I'm going to provide the [57:52] variable name name. The length function [57:55] is going to uh is going to count how [57:57] many characters are stored in the [57:59] specified variable name. Let's execute [58:02] the code and we have 15 in the output. [58:06] So there are total 15 characters in the [58:09] uh string. Right? The spaces are also [58:12] counted. Let me add [58:15] two spaces, one at the end and one at [58:18] the beginning. and we have length 17. [58:22] Now here I am providing a variable name. [58:26] Right? Now we can directly provide a a [58:29] string value uh to it as well. Let's [58:32] provide let's say admin. This time the [58:35] length function is going to check length [58:38] of this provided string admin which is [58:41] uh five I guess. As you can see now I [58:45] want to convert all these lowerase [58:48] letters into uppercase. Print syntax is [58:52] simple. First write the string or [58:55] variable name where you want to perform [58:58] this conversion uh let's say name. Now [59:02] the function for converting lowerase [59:04] letters into upper case is upper sorry [59:09] upper. [59:12] Now the way this upper function works, [59:14] it will take all the lowerase letters [59:17] stored in the specified variable name [59:19] then convert them into uppercase. As [59:22] simple as that. [59:24] As you can see all the lowerase letters [59:26] have been converted into the uppercase. [59:30] Right? Now just like the length [59:32] function, we can directly provide a [59:35] string value to the upper function. [59:38] Let's say root. This time the upper [59:40] function is going to take this root or [59:44] lowerase all these lowerase letters and [59:46] convert them into uppercase as you can [59:49] see. Now let's convert lower case uh [59:53] sorry uppercase letters into lower case. [59:56] Let's add uh uppercase [59:59] letters in this string. root user [60:04] name dot function for converting [60:07] uppercase to lower case is [60:10] lower parenthesis. And uh this time the [60:14] lowerase function is going to take all [60:16] the uppercase letters stored in the name [60:19] variable then convert them into lowerase [60:23] letters. [60:25] As you can see the root user which is in [60:28] uppercase letters has been converted [60:31] into lowerase. Just like the length and [60:34] upper functions we can directly provide [60:37] a string value uh to it. So let's say [60:41] root in uppercase. [60:43] This time the lower function is going to [60:45] convert these uppercase letters into [60:49] lower case as you can see here. Now [60:52] let's capitalize the string. Uh, let me [60:54] get rid of uh uppercase letters. [60:59] Print name dot [61:03] capitalize [61:05] parenthesis. [61:07] Now the capitalize method converts the [61:11] first letter of a string into into [61:15] uppercase. So here in this string the [61:18] first letter of this string is R. So [61:22] capitalize function is going to take [61:23] this first letter and convert it into [61:26] uppercase. As you can see R of the root [61:29] has been converted into the uppercase. [61:32] Right? So that's the capitalize [61:34] function. We have a similar function [61:36] called title. So name dot title. Now the [61:41] title function capitalizes the first [61:45] letter of each word in a string. Right? [61:49] In this name string as you can see we [61:51] have three words and all are in lower [61:54] case. Now the title function is going to [61:57] take the first letter of each word in [62:00] this string then convert into uppercase [62:04] as you can see right the next function [62:07] that we are going to cover is replace. [62:10] I'm going to replace let's say root with [62:13] something else. So print [62:17] name. Now write the replace method. Now [62:21] you have to tell the replace function [62:24] two things. One, what you want to [62:27] replace. I want to replace the word [62:30] root. So write the root comma. Now [62:35] specify what you want to replace the [62:38] root with. I want to replace root with [62:42] demalu. [62:44] Let's execute the code. As you can see [62:46] the demalu has the root has been [62:49] replaced by the dimallu. So the way [62:51] replace function works is it searches in [62:54] the string that you have specified to [62:57] it. In my case it is name. So it will [62:59] search for the word root in the value [63:02] stored in the name variable. It will [63:04] search for the root. If it finds the [63:07] root then it replaces it with dalu. So [63:10] it did find the root and it was replaced [63:14] by demalu. As you can see now let's [63:18] print just the name variable. [63:22] As you can see guys at line number four [63:25] we printed name. Here we have the [63:28] original string being printed root admin [63:31] user. So the replace function doesn't [63:33] actually modify the actual value or [63:37] data. So what it does it takes the value [63:41] that you supply to it makes changes then [63:44] returns it. It doesn't modify the [63:48] original string. Now if you want to use [63:50] the modified string later in the program [63:54] then what you can do is store that [63:57] modified uh value in a new variable. [64:01] Let's say replace [64:04] replaced value equal to this [64:08] print [64:10] replaced. The replace function is going [64:13] to replace the word root with demalu [64:16] then return or assign the modified [64:20] string to the replaced variable. Then [64:22] down here I am printing the replaced [64:26] variable which is holding the modified [64:28] value as you can see. Now, next thing [64:31] that uh that um I'm going to cover is [64:35] the string slicing. The string slicing [64:39] simply means slicing or extracting a [64:42] specific portion of a string. For [64:45] example, we have this this string. I [64:48] don't want to display this portion. I [64:51] only want to display or print this [64:54] particular portion. To achieve this, we [64:57] have to use the string slicing. Uh let's [65:01] make it uh a bit realistic. So what I'm [65:04] going to do is uh create a URL variable [65:06] and assign it a URL. https [65:10] google.com [65:12] print [65:14] URL. As you can see, we have printed [65:17] this complete URL. Now I don't want to [65:20] print this portion, right? I only want [65:22] this google.com. [65:24] Okay. So, inside the print function, [65:26] write the exact variable name where you [65:30] want to perform this slicing. Now, write [65:33] the square brackets like this. Now, [65:36] specify a number. I want to skip these [65:40] letters. So, how many letters are in [65:43] these? 1 2 3 4 5 6 7 8. So, specify [65:48] eight then colon. it will basically skip [65:52] the first eight characters or whatever [65:55] number you specify here. So it will skip [65:58] the first eight characters in this [66:00] string and print the remaining uh [66:04] characters in this uh specified string [66:06] which is URL. As you can see we have the [66:10] expected output. We have successfully [66:13] sliced or extracted this portion. We [66:16] skipped this portion right? So whatever [66:19] number you specify before the column, it [66:22] will skip those many characters from the [66:24] left and uh print the remaining [66:27] characters. As you can see, now we can [66:30] also extract from right. To extract from [66:33] right, we need to use minus. So minus 4. [66:37] So minus4 means it will skip the four [66:40] characters from the right. So four [66:42] characters are 1 2 3 4. [66:46] And as you can see it has skipped these [66:49] four characters. [66:51] Now I only want to print this portion [66:55] Google. I want to slice this string from [66:59] the middle. Right. Well here we need to [67:02] use both positive and negative indexing. [67:06] First I want to skip these many [67:09] characters from the left. So I think [67:11] they are total eight. So specify 8 colon [67:15] and I want to skip 1 2 3 four characters [67:19] from right. So write uh minus4. Let's [67:24] execute the code. As you can see we have [67:28] Google. It skipped eight characters from [67:31] the left and minus4 it skipped four [67:34] characters from the right. Now next [67:37] function that we have is count. Uh let's [67:39] say root user root admin [67:44] print. Okay, let's uh rename it to name [67:50] name dot count [67:54] root. Now the count function basically [67:57] counts how many times a substring is [68:00] appearing inside a string. Now this is a [68:03] complete string and this root as you can [68:06] see this is part of this substring. [68:08] Substring means uh a string that is part [68:12] of a bigger string. It counts how many [68:15] times the specified substring is [68:18] present. So the count function is going [68:21] to check for this root substring in this [68:24] name variable. How many times it is [68:26] appearing. Let's execute. We have two. [68:30] It means the root is present two times [68:33] in this string. Right? It indeed is [68:36] true, right? It is appearing twice. [68:39] Let's add another root. We should get [68:42] three. As you can see, root is appearing [68:44] three times. Now, next method that we [68:48] have is uh is called strip. The strip [68:53] method is used to remove spaces from a [68:57] string. It removes spaces from end and [69:01] beginning of a string. So let's add one [69:04] space at the end and one space at the [69:07] beginning of this string. [69:10] Print let's check length of this string. [69:14] length of uh the [69:17] string before [69:20] applying [69:24] strip [69:26] function is [69:28] length [69:30] name and let's execute the script. As [69:34] you can see length of this string before [69:36] applying strip is 27. Now let's apply [69:40] the strip function. Specify the variable [69:44] name or string where you want to remove [69:46] spaces. Name dot strip. [69:51] Now let's print the name variable. Now [69:55] the way the strip function works is it [69:59] removes spaces from the beginning and [70:02] end of a string. So it will remove these [70:04] two spaces. Let's execute this code. As [70:08] you can see length before applying [70:12] strip. Okay. Uh let's uh write uh [70:18] length after [70:21] applying [70:22] strip [70:29] function. [70:33] As you can see, we have the same output. [70:35] Length before applying and length after [70:37] applying strip 27. Just like the replace [70:40] function, the way strip function works [70:43] is it doesn't actually modify the actual [70:46] value. Okay, it basically takes the [70:49] value that you supply to it then [70:52] modifies it and returns the modified [70:56] value. Here we are not storing the [70:59] returned value that the strip returns. [71:03] So [71:05] name equal to name dot strip. This time [71:09] we will have a different output. As you [71:11] can see length before applying strip 27 [71:14] after applying 25 because it removed two [71:18] spaces one from the end one from the [71:20] beginning. So length became 25. Now let [71:24] let me explain this portion here. uh as [71:26] I mentioned earlier the strip function [71:29] doesn't actually modify the the actual [71:32] value of a string. So what it does is it [71:36] takes the value that you specify or [71:39] provide to it makes changes it removes [71:42] spaces then returns that value. Right [71:46] now here we are storing the returned [71:49] value in the name variable. Now the name [71:52] variable is storing the returned or [71:55] modified value. So old value gets [71:58] overwritten by the new modified value. [72:02] So we get 25. And of course you can [72:05] assign the modified value in a different [72:08] variable like this name one. [72:13] So that's how this strip function works. [72:16] Now there are two variants of this strip [72:20] function. R strip and the L strip. So R [72:24] strip removes space or spaces from the [72:27] right side of the string. Let's execute. [72:31] As you can see, we have 26 because our [72:35] strip only removes spaces from the right [72:38] side. Since there is one space, so it [72:42] was removed. So length is 26. [72:47] We also have the L strip. It removes [72:50] space or spaces from the left side of a [72:53] string which is this. It removed one [72:55] space. So we have 26. [72:59] Strip removes spaces from both sides and [73:02] R and L strip remove spaces from right [73:07] and left sides respectively. In this [73:10] video we are going to learn about string [73:14] formatting. It is an important concept [73:16] for writing clean and efficient code. [73:20] String formatting in Python allows us to [73:22] insert variables or values directly into [73:26] strings. Up until now we have been [73:28] combining variables and strings using [73:32] commas. Right now we will learn how to [73:34] achieve the same thing but in a much [73:37] more efficient and elegant way. Now [73:40] let's dive into the practicals. Let me [73:43] create a few variables. Name equal to [73:46] root, ID equal to 1,00 and print. I want [73:51] to insert these two variables directly [73:55] inside my string. To achieve this, we [73:57] need to use the fring. F string stands [74:01] for string formatted. To enable fringing [74:05] or string formatting, we need to write [74:08] the f letter immediately after the [74:12] opening parenthesis like this. Now [74:15] within quotes, we can insert variables [74:17] inside the string. My name is within [74:22] curly brackets write the variable name [74:24] that you want to access. Let's execute [74:27] the code. As you can see, my name is [74:29] root. We have successfully inserted the [74:33] name variable inside the double quotes [74:36] or the string. The syntax is simple. [74:40] First enable the f string by writing f [74:44] at the beginning. Then uh to insert [74:46] variables we need to write the exact [74:49] variable name or variable names within [74:52] the curly braces like this. Now let's [74:56] insert the ID variable. ID equal to [75:00] within [75:01] quotes ID and we have accessed the both [75:06] of these variables ID and name. My name [75:09] is root ID is 1,000. Like I mentioned [75:13] earlier, we can insert not only [75:15] variables also mathematical expressions [75:18] within a string using string formatting. [75:22] Just write your expression within uh the [75:26] curly braces like this. Well, let's say [75:29] 34 [75:31] into 4. Let's execute the code. And we [75:37] have the output 136. So, it successfully [75:42] performed this mathematical [75:45] calculation. Right? Similarly, you can [75:48] perform any calculation. [75:50] Let's say 48 [75:53] 9 divided by 15. Let's see what we get [75:57] in the output. [76:00] Okay, I forgot the division operator. [76:04] So, 49 divided by 15 and we have the [76:10] expected output. My name is root and [76:12] this is the result of this division. [76:15] However, the decimal places are out of [76:18] control. Right? We have these many [76:20] decimal places. I only want to display [76:23] maybe two or three decimal places. To [76:27] control the decimal places after the [76:30] second number, write colon dot write to [76:36] F. Now this time it will only display [76:40] two decimal places or whatever number [76:44] you specify after dot as you can see. So [76:47] that's the beauty of the string [76:49] formatting. It not only allows us to [76:54] insert variables or mathematical [76:56] expressions within a string, it also [76:59] allows us to control these decimal [77:02] places. Let's say four. Now it will [77:05] display four decimal [77:08] places. As you can see, this way it [77:10] looks much more cleaner and readable. It [77:14] is easier to write and read the code [77:17] this way. Another method for uh [77:20] formatting string is the method called [77:24] formatter. So let's remove this [77:29] print. [77:32] Then the curly brack bracket after the [77:36] closing quote write dot then format [77:41] within format parenthesis write the [77:43] variable name that you want to insert. [77:45] Let's execute the code. Okay, we have an [77:49] error at line number three format name. [77:52] Okay. Okay, we need to remove string [77:56] formatting because with format method we [77:59] can't use the f string. So remove it and [78:03] the code should work just fine and my [78:06] name is root. So the way the format [78:09] method works is first we need to mark [78:12] the spot or spots where we want to [78:15] insert the variable. Now the spots are [78:19] marked by the curly brackets. So the [78:22] variable will be inserted in this curly [78:26] brackets spot. Here I have marked this [78:30] spot and the format method is going to [78:32] insert the name variable here in this [78:36] marked spot. Let's say ID is [78:41] ID. This is the second spot. And now [78:44] provide the variable name ID. Now format [78:47] method is going to insert name variable [78:51] in the first spot. the ID variable in [78:53] the second spot that has been marked as [78:57] you can see. Okay, Fring. Okay, we have [79:02] this F string enabled. I did not enable [79:06] it. It is the Z code editor that is [79:10] automatically inserting this F string at [79:13] the beginning. I don't know why it is [79:15] doing it, but yeah, that's what it is. [79:18] Now, let's uh execute the code. As you [79:20] can see, my name is root, ID is 1,000. [79:23] So that's how the format method works. [79:26] First, we need to mark the spots where [79:29] we want to insert variables using curly [79:32] braces. Then uh inside the format [79:35] method, we need to write the variable [79:38] names that you want to insert. In this [79:41] section, we will explore operators and [79:43] mathematical operations in Python. Uh [79:46] this is a theoretical introduction which [79:48] is absolutely essential. Each type of [79:51] operator will be covered practically one [79:54] by one in the upcoming videos. So what [79:57] exactly are operators? Operators are [80:00] symbols used to perform specific [80:03] mathematical or logical operations on [80:06] data values or variables. They take one [80:09] or more values as input and produce a [80:13] new value as output based on the defined [80:17] operation. For example, the plus sign is [80:20] an arithmetic operator that performs [80:23] addition. It takes two numerical values [80:26] as input and returns their sum. [80:29] Similarly, Python provides other [80:31] arithmetic operators like subtraction, [80:33] multiplication, division and modulus. [80:36] These operators are essential for [80:39] performing various calculations and are [80:42] the building blocks of mathematical [80:45] expressions. They are used extensively [80:47] in programming or specifically the math [80:51] ccentric applications. Operators in [80:53] Python can be broadly categorized into [80:56] four main groups. Arithmetic, [80:58] relational, logical and equality [81:01] operators. Arithmetic operators are used [81:04] to perform basic mathematical [81:07] calculations. These are the arithmetic [81:09] operators. Addition, subtraction, [81:11] multiplication, division and modulus. [81:15] Then we have relational operators also [81:17] known as the comparison operators. They [81:20] compare two values and return a boolean [81:23] result true or false. Examples include [81:26] less than, greater than, greater than [81:29] equal to, less than equal to ATC. They [81:31] are often used in if statements and [81:34] loops to control the flow of program. We [81:38] also have logical operators. They [81:40] combine multiple conditions and return a [81:43] boolean result. Examples of logical [81:46] operators include and, or, and not. They [81:50] are useful when you check multiple [81:52] conditions at the same time. We also [81:54] have some other operators that we will [81:57] explore as we progress in the course. In [82:00] the upcoming videos and sections, we [82:03] will explore each category of operators [82:05] in detail one by one. In this video, we [82:09] will perform arithmetic operations. We [82:12] are going to perform the basic [82:14] arithmetic operations. Let's start with [82:17] addition. [82:18] addition is [82:22] 45 + 56. [82:27] The second arithmetic operation [82:29] operators that we have is uh [82:32] multiplication. Multiplication is [82:36] into [82:39] 56 into 8 67. [82:43] Then we have subtraction. [82:46] Subtraction is [82:50] 34 minus uh 4 [82:54] print then we have modulus [82:58] remainder is [83:03] 45 modulus by 4 and finally we have [83:08] division. [83:10] division division is [83:14] 45 divided by 5. So these are the basic [83:20] arithmetic operators that we use in all [83:24] the math ccentric applications. [83:27] So let's execute the script and see if [83:30] it is working as it should. [83:33] Okay, we have the expected result. [83:36] addition, multiplication, subtraction, [83:38] remainder, division. So everything is [83:41] working as it should. Now instead of [83:44] directly using values, we can store [83:48] values in variables. Then use the [83:50] variables. This is the convenient way or [83:54] the preferred way to perform [83:56] calculations. First store the values in [83:58] variables. A equal to 67, B= 6. [84:03] Let's replace values with a + b [84:08] a into b [84:12] a subtract [84:15] by b [84:17] a modulus b [84:20] a divided by b. Let's execute the [84:23] script. It will produce the same result [84:27] as you can see. However, here we have in [84:30] division, as you can see, we have a lot [84:32] of decimal places. [84:35] Now, to control decimal places with [84:37] variables, we need to use the string [84:40] formatting option, right? So, F enable [84:44] the string formatting and put sorry, not [84:47] here. I think division is the last [84:51] operation. So, enable the string [84:54] formatting. Now put this expression [84:58] within the curly brackets like this [85:02] colon point how many decimal places you [85:06] want. Let's say 2F. So after the second [85:10] variable write colon dot 2F. 2F means it [85:13] will display two decimal places. Uh [85:18] let's execute the script and we have the [85:20] perfect output as we wanted. So that's [85:24] it for this video. In the next video, we [85:26] are going to create a dynamic [85:28] calculator. In this video, we are going [85:31] to talk about the boolean data type and [85:33] relational operators in Python. These [85:36] two concepts are deeply interconnected. [85:39] They work together to help your program [85:41] make decisions. A boolean value can be [85:44] only true which is represented or [85:46] interpreted as one in numerical context [85:50] or false with uppercase f which is [85:52] represented as as zero in the numerical [85:55] context. Boolean operations work by [85:58] taking one or more inputs and these [86:01] inputs must be either zero one or true [86:05] false. The boolean operation then [86:07] produces an output that is always either [86:10] true or false. Boolean operations are [86:13] used with logical operators like and or [86:16] not. They are widely used in programming [86:19] to make decisions particularly in [86:22] conditional statements, comparisons and [86:24] logical operations that control the flow [86:27] of program. Let's dive into the [86:30] practicals. I'm going to demonstrate the [86:33] the boolean data type with the [86:35] relational uh operators. The output of a [86:39] relational operation is always a [86:41] boolean. It is either true or false [86:44] depending on the expression being uh [86:47] being evaluated. So print [86:51] I'm going to check if 12 is greater than [86:54] six. Now this is called the relational [86:57] operator. Greater than relational [86:59] operator. We will cover the relational [87:01] operators in detail in the conditional [87:04] statements section. Okay. So what Python [87:08] is going to do? It is going to evaluate [87:10] this expression if 12 is greater than [87:14] six. Output of a relational operation is [87:18] always either true or false. Now if [87:21] condition is true then it returns true. [87:24] If it is false then it returns false. [87:26] What do you think the output of this [87:29] operation is? This is obviously true [87:31] right? 12 indeed is greater or bigger [87:34] than six. So let's see what we get in [87:36] the output. We have the output true, [87:39] right? Because this expression is being [87:41] evaluated to true. Now uh let's say 12 [87:46] greater than 60 63. What about this? [87:49] This is false, right? 12 is not greater [87:52] than 63. So it will return the boolean [87:55] output of false as you can see. So [87:59] that's the boolean data types for you. [88:01] Now boolean data types are used for [88:04] decision making in in if statements, [88:07] loops and other control structures that [88:09] we will cover in the upcoming [88:12] uh upcoming sections. Now we can also [88:15] store a boolean value to a variable. For [88:18] example, a equal to true. Remember guys [88:22] the T of true is always in upper case [88:26] and f of false is always in upper case [88:31] as well. Okay [88:34] like this a [88:38] now do not surround the boolean values [88:42] true and false within within quotes. If [88:45] you do surround within quotes then [88:46] Python will not treat them as as a [88:49] boolean value rather it will treat them [88:51] as a string. For example, let's uh check [88:54] the type of uh data that the variable a [88:58] is storing. [88:59] As you can see class bool it means it is [89:02] uh the a variable is storing a boolean [89:04] data type. What if I surround this [89:07] within ports [89:09] now we should have string as you can [89:11] see. So, so whenever you put anything uh [89:14] between quotes whether single or double [89:17] quotes, Python treats that as a as a [89:20] string. In this video, we are going to [89:23] talk about inputs in Python. How to [89:26] collect or take inputs from users or [89:30] keyboard. When you create programs, you [89:33] will often need to ask users for some [89:36] kind of input. This input could be [89:39] anything. a name, a number, or even a [89:42] choice between different options. Once [89:44] we collect the input, we can process it [89:47] and then display a result back to the [89:51] user based on what they entered. For [89:54] example, if you are building a [89:56] calculator, you need to collect numbers [89:58] from the user so that your program can [90:01] perform operations like addition, [90:03] subtraction or multiplication. [90:05] Understanding how to take user input is [90:08] one of the most important and [90:10] fundamental steps in making your program [90:13] interactive and dynamic. Now let's dive [90:16] into the practicals. [90:19] Let me create the variable x. X equal to [90:23] input. The X variable is going to store [90:26] the user input. Now the input function [90:29] in Python is used to collect user [90:32] inputs. It basically allows us to enter [90:35] inputs from the keyboard. Now within [90:38] parenthesis quotes within quotes we need [90:41] to specify a prompt. Prompt simply means [90:44] the message that you want to display to [90:47] users. Here we need to specify what your [90:51] program expects user to enter. I'm going [90:54] to request user to enter a number. [90:57] Right? So enter [90:59] enter any number [91:03] and let's print the variable x which is [91:07] going to store whatever a user enters [91:10] from the keyboard. [91:13] You have entered [91:16] x. Let's run the script. Enter a number. [91:20] As you can see guys, this is our prompt [91:22] which is requesting user to enter a [91:25] number. And then we have this cursor. It [91:28] is basically waiting for me to enter [91:32] some input or a data. So let's enter a [91:36] number. [91:38] Now press enter. As you can see, you [91:40] have entered 5 6 5 6. Right? So input [91:45] function allows us to enter inputs from [91:48] the keyboard. And whatever input you [91:51] enter that input gets stored in the [91:54] variable that you specify here. So x is [91:57] storing a user input. Then down here I [92:00] am printing the x. Right? That's why we [92:03] have the the output you have entered 56 [92:06] 56. This is exactly what I entered. Now [92:10] here we have a minor problem right? [92:13] There is no space between the user input [92:17] and and the prompt which doesn't look uh [92:20] good. It can easily be fixed. After the [92:24] prompt create a space like this. [92:29] Now we have a much better output. You [92:32] can make it even uh better or fancier. [92:36] just uh write something like uh greater [92:39] than sign for a better user experience [92:42] like this. [92:46] Now let's create a few more input fields [92:49] for a better clarity. Now I'm going to [92:52] request user to enter their name. Name [92:56] equal to [92:58] input. [93:01] Enter your name. [93:04] Let's print name. [93:08] Hello [93:10] name. [93:12] So enter any number. Let me enter 78. [93:16] 78. It gets stored in the variable x. [93:19] Press enter. [93:21] Now enter your name root. Now the root [93:25] gets stored in the name variable. Down [93:28] here I'm printing both of these [93:30] variables. Right? Press enter. As you [93:33] can see you have entered 78 hello root. [93:37] So these are the exact inputs that I [93:40] entered. Right? This way you can create [93:44] as many input fields as you like. [93:49] Now let's move on to the most important [93:52] part of the input function. Let me get [93:56] rid of these two lines. [93:58] By default, the input function treats [94:02] all inputs as string. So, whatever you [94:06] enter, the input function is going to [94:09] treat that as as a string. Let me [94:12] actually show it uh to you. [94:16] Here I am going to enter 56. Okay. So, [94:20] what I'm going to do is check its type. [94:22] So we have the type function which [94:24] checks the type of data that a variable [94:27] is storing. Right? So here type x. [94:32] I'm going to enter a number 56. Press [94:35] enter. As you can see guys, x is a [94:38] string even though it is clearly a [94:40] number. This is because that's how the [94:43] input function works. By default, it [94:47] treats all the user inputs as strings. [94:51] whether you enter a string or a number, [94:55] it is going to treat them as a string. [94:59] Now, this can create problems when [95:01] performing calculations or mathematical [95:04] operations because to perform [95:07] calculations, we need numbers. For [95:09] example, if you are building a [95:12] calculator, then you have to ask user to [95:15] enter numbers. But when you enter [95:18] numbers, the input function is going to [95:21] treat that as a string. On strings, you [95:24] can't perform calculations. To perform [95:26] calculations, we need numbers like [95:29] integers, decimal numbers, ATC. Let me [95:32] try to perform calculations. X + 6. X is [95:38] storing the user input plus 6. [95:42] Let me enter a number. As you can see, [95:45] we have an error here. Can't concatenate [95:49] strings. We cannot perform addition or [95:52] any operation with strings. We need the [95:55] numbers for that. In the next video, we [95:58] are going to fix this. We are going to [96:00] continue from where we left off in the [96:03] previous video and learn about the type [96:06] casting. Type casting allows us to [96:08] convert one data type into another. For [96:10] example, turning a string into an [96:13] integer, an integer into float or float [96:16] into an integer. Now, why do we need [96:20] type casting? Well, this is extremely [96:23] important in Python because as we saw in [96:26] the previous video, whenever we take [96:28] input from a user, input function treats [96:32] that input as a string by default. The [96:35] problem is that strings can't be used in [96:39] mathematical calculations. So even if a [96:41] user enters a number, Python still sees [96:44] it as a a string or text. As a result, [96:48] we will not be able to perform any [96:50] calculations with it. Therefore, to [96:53] actually perform calculations or use the [96:55] value correctly, we need to convert that [96:58] input from a string into the correct [97:01] data type such as integer or float. [97:04] That's exactly what type casting helps [97:07] us uh do. It converts one data type into [97:10] another. Now let's dive into the [97:13] practicals. I'm going to start with a [97:15] simple uh example. Then later we will [97:19] convert user inputs into numbers. Okay. [97:23] So a equal to [97:26] 45.56. [97:28] Now this is a decimal number, right? So [97:31] what I want to do is convert this [97:33] decimal number into an integer. I want [97:36] to remove this decimal part. So a equal [97:40] to int. Now int is a function that [97:43] converts other data types like float [97:46] into an integer. Now within parenthesis [97:49] specify the value or variable that you [97:51] want to convert into the integer. So [97:54] what integer function is going to do? It [97:56] will take the value stored in the [97:58] variable a and convert it into an [98:02] integer. It will remove the decimal part [98:06] from this value. Then store the integer [98:09] value into the variable a. Let's print [98:16] a. As you can see guys, 45 the decimal [98:20] portion has been removed. [98:23] Let's print it before the conversion or [98:26] type casting. [98:28] As you can see guys, here at line number [98:31] two, I'm printing a before converting it [98:34] into an integer. So we have 45.56. [98:39] At line number three, I'm converting [98:40] this decimal value into an integer. And [98:44] after converting it into an integer, we [98:47] have the output 55. [98:50] Right? Let's actually check the type as [98:54] well [98:57] a [99:00] as you can see type integer [99:05] and here we have the type float because [99:08] before converting it into an integer [99:11] here this is a decimal number. So we [99:13] have the float which represents decimal [99:16] numbers and here after converting it [99:18] into an integer it has been converted [99:21] into an integer. So we have the data [99:24] type int. Similarly you can convert [99:27] other data types uh as well. For example [99:31] a this is an integer right? Let's [99:34] convert it into a float. The function [99:36] for converting an integer into a decimal [99:39] number is float. So float a. So float is [99:43] going to take the value stored in a and [99:47] convert it into a decimal number or [99:50] float. Let's execute the code. As you [99:52] can see guys, here it has added the [99:55] decimal portion 44 45.0. Right? Even [99:59] though the original value of a doesn't [100:02] contain any decimal portion. But here [100:05] the float function converted this [100:08] integer into float by adding the uh dec [100:10] decimal places. Now what happens if you [100:15] put a number within code okay before [100:19] that type [100:23] a. Now it is going to show integer. [100:26] Right now what happens if I put this [100:28] integer within single or double quotes? [100:32] As you can see now we have string. So if [100:36] you put anything within single or double [100:38] quotes, Python is going to treat that as [100:41] a string whether it is a number, boolean [100:45] data type or a string. Similarly guys, [100:48] we have many other functions for for [100:50] performing type casting like uh string [100:54] list tupal ATC. We will cover all these [100:58] functions as we as we progress in the [101:00] course. Now let's jump into the input [101:03] function. How to convert the user inputs [101:06] into a number like float or integer. [101:10] A equal to input [101:14] enter a number. [101:18] The steps remain the same. So a equal to [101:23] int. I want to convert user whatever [101:25] user enters into an integer. So within [101:29] parenthesis write a. Now what is a? A is [101:32] storing uh the user input. So whatever [101:34] user inputs that gets stored in a then [101:38] we are converting that a into an integer [101:41] then storing that back in the variable [101:44] a. [101:48] Enter a number as you can see. Now let [101:51] me try to add let's say user input to [101:55] seven. Let's execute the code. Enter a [101:59] number. Press enter. This time we have [102:03] 76. Right? So what happened is that I [102:07] entered 67. It got stored in the a [102:10] variable. Then down here I'm converting [102:13] the variable a into an integer because [102:16] by default as we already know the input [102:18] function treats input as string. So I'm [102:21] converting string into an integer then [102:24] storing it back in the a. Then here I am [102:28] uh performing the addition. So whatever [102:30] user enters I am adding + 7 to it. Okay. [102:35] Now what happens if I remove this [102:37] conversion or type casting [102:40] it will throw an error. As you can see, [102:44] we have the type error because here I [102:47] entered a number which is 34. Python is [102:52] treating it as a string. So here Python [102:55] is trying to add string to a number [102:58] which is not a valid expression. But if [103:01] I convert the user input into integer or [103:05] float, then yeah, we can perform [103:07] calculations easily. Now let's uh accept [103:11] second input [103:18] b equal to int b. Now I'm going to add a [103:23] + b. Whatever user enters I'm going to [103:26] add those two numbers. Enter first [103:28] number. Enter second number. As you can [103:31] see we have 61. [103:33] So here the first number gets stored in [103:36] the a. second number gets stored in the [103:38] B. Now I'm converting both of these [103:42] inputs into integers. Right? So here A [103:46] equal to int a. So A gets converted into [103:50] integer. Then it is stored in A. Then B [103:54] as you can see I'm converting B also [103:57] into an integer. Storing that converted [104:01] value in B. Then down here I'm [104:03] performing the calculations. Now a [104:06] simpler way to convert user inputs into [104:11] numbers or other data type is simply [104:14] specifying [104:16] uh the int function here like this int [104:19] open opening parenthesis. Now close the [104:22] opening parenthesis of int at the end [104:25] like this int [104:28] close it here and we will have the same [104:33] output. As you can see, it is not [104:35] throwing any errors. So what basically [104:38] is happening? Python first processes the [104:40] input function. Once user enters an [104:43] input, then the int function is going to [104:46] convert that input into an integer and [104:50] store the converted value back to the A [104:54] and same steps are repeated for B. [104:58] Right? We can also use you know [105:02] load like this. [105:08] As you can see now we have uh output [105:10] with decimal values. Okay, we will cover [105:13] this more in details in upcoming videos. [105:17] In this quick video we will take a look [105:19] at the plus operator in Python. Yes, it [105:21] is an arithmetic operator that performs [105:25] addition, right? But in Python, it does [105:27] more than just math. The plus operator [105:31] can also concatenate or combine strings [105:34] together. Its output depends on how and [105:37] where you use it. With numbers, it [105:40] performs addition. With strings, it [105:43] joins or concatenates the strings. With [105:46] lists or tupils, it combines them. [105:48] Python is smart enough to change the [105:51] behavior of plus based on the data type [105:54] you are working with. Now, let's dive [105:56] into the practicals. So I'm going to [105:58] start with a simple example. [106:01] So print. [106:05] Now this simple print statement is going [106:08] to add two numbers. As you can see it is [106:11] working or behaving expectedly as it [106:14] should. Now [106:17] what happens if I [106:21] try to add two strings root plus [106:26] uh let's say demalu [106:30] now this time as you can see guys it has [106:32] concatenated [106:34] these two strings right so that's how [106:36] the plus operator works when you provide [106:40] it two numbers then it adds them and [106:44] when you provide create two string [106:46] values then it concatenates them or it [106:50] merges them. You can concatenate as many [106:54] strings as you like [106:57] like this plus [107:01] space. So this time I'm concatenating [107:04] root plus here uh this is a white space. [107:09] So it will add space between these two [107:12] words. [107:14] Let's uh execute. [107:17] As you can see, it also works with [107:19] variables. So, what I'm going to do is [107:21] create two variables. Let's say fame [107:25] equal to [107:27] root [107:30] lame equal to [107:34] admin. [107:36] Print. Now I want to display root and [107:41] admin as a full name which is simple. [107:44] Print the full name [107:50] is [107:52] fame [107:54] plus all I need to do is concatenate [107:58] these two variables like this. So since [108:02] these two variables as you can see they [108:04] store string values. The plus operator [108:08] is going to take these two variables [108:10] then concatenate them into a single [108:14] string. As you can see full name is root [108:18] admin. And if you want to add space a [108:21] space between these two words then we [108:26] can concatenate a white space like this. [108:30] Make sure that you know you add plus [108:32] signs appropriately like this. after fn [108:34] name then plus wide space plus as well. [108:39] Now this time we have a much better or [108:41] formatted output. So guys like I [108:44] mentioned uh earlier in the video the [108:47] behavior of the plus operator depends on [108:50] the type of data you feed it. If you [108:53] feed it two numbers then it adds them or [108:57] calculates them. If you feed it two [109:00] string values, then it concatenates or [109:02] combines them. Now what happens? What [109:06] happens if you attempt to [109:11] do something like this? Uh here I'm [109:15] providing it two different data types 12 [109:19] + root. 12 is an integer of course root [109:23] is a string. Let's see. And we have an [109:26] error. unsupported upper hand plus int [109:29] and string right so here we have an [109:31] obvious error because Python is confused [109:34] here what I'm trying to do right here [109:37] I'm trying to add a number with string [109:40] that's why we have an type error so it [109:44] it only works if you provide it the same [109:47] data type so if you provide two strings [109:50] it concatenates them if you provide two [109:52] numbers it adds them so plus also works [109:56] Same with other data types like tupils [109:59] and lists as well that we will cover [110:02] later in the course. We are going to [110:05] continue from where we left off in the [110:08] previous video. In this video, we will [110:09] perform arithmetic operations based on [110:12] user inputs. We will ask the user to [110:15] enter numbers and then perform [110:18] calculations on them. This is where we [110:21] will bring together everything that we [110:24] have learned so far. Arithmetic [110:26] operations, type casting and combining [110:29] them with user inputs to create a [110:32] complete interactive or dynamic program. [110:35] Now let's dive into the practicals. [110:37] First we are going to collect or gather [110:40] the inputs from user. Then we will [110:43] perform arithmetic operations on those [110:46] inputs. So a equal to input. [110:52] Now we need to to convert the user [110:56] inputs into integers because as we [110:58] already know by default the input [111:01] function treats all inputs as string. So [111:04] we can't therefore we can't perform [111:07] calculations on strings. Right? So first [111:10] we need to convert [111:12] the input into integer. So int opening [111:16] parenthesis close the integers [111:19] parenthesis [111:22] same uh thing repeat the same thing for [111:24] uh the second input integer and close [111:27] the integer function. So whatever input [111:31] a user enters that input will be [111:33] converted into integers once it is [111:36] converted now we can uh we can basically [111:39] perform mathematical operations with the [111:42] user inputs. So let's uh perform [111:46] arithmetic operations. [111:48] Addition is a + b. [111:53] Print [111:56] multiplication is [111:59] a into b. [112:02] Print remainder [112:06] is [112:09] a modulus b [112:13] and the division a division is [112:19] a divided by [112:23] b. We also have the subtraction of [112:26] course. Print [112:29] subtraction is [112:32] a minus b. Let's execute the script. [112:36] Enter first number 23 [112:39] 5. As you can see guys, we have the the [112:43] expected output or well formatted [112:47] output. We are asking user to enter [112:50] first number, second number. Then we [112:53] have converted the user inputs into [112:56] integers as you can see. Then down here [112:59] we are performing the arithmetic [113:00] operations on the user inputs. So this [113:04] is as easy as that. [113:07] Now what I'm going to do is instead of [113:10] directly performing arithmetic [113:13] operations in the print function, I'm [113:14] going to store the results in variables. [113:18] For example, sum equal to a + b. So what [113:22] basically is happening here? We are [113:24] calculating a + b then assigning that [113:28] output to the sum variable. Now instead [113:31] of writing a plus b, we can simply use [113:34] the sum variable because the sum [113:37] variable is holding the output of a + b. [113:42] Now benefit of storing result of a [113:45] calculation in a variable is that we can [113:48] reuse that result later in the program [113:51] wherever it is needed. For example, if I [113:54] want to use the sum of a + b somewhere [113:59] down here in the in the program, then I [114:01] can simply use the sum variable instead [114:05] of uh you know writing the expression a [114:07] + b. So it is very convenient and uh the [114:11] standard way to write the mathematical [114:14] expressions in programming. Now same [114:17] thing we can repeat for other [114:19] operations. Multiplication equal to a [114:22] into b. So here let's write uh [114:30] multi. The multi variable is storing the [114:34] result of a into b. Let's execute the [114:37] script. [114:39] As you can see, we have the expected [114:41] output, right? Let's uh go for uh [114:44] modulus as well. Modulus equal to a a [114:50] modulus b. We can give it uh an [114:54] appropriate variable name remainder. [114:57] Remainder. [114:59] Let's replace a modulus b with the [115:03] remainder. Remainder variable. The [115:05] remainder variable is of course storing [115:07] the result of a modulus b. Let's uh run [115:12] the script again. As you can see guys, [115:14] we have the expected output. Similarly, [115:17] you can create variables for rest of the [115:21] arithmetic operations that we have [115:24] performed and store the result or output [115:27] in those variables. then use the [115:29] variables here instead of writing the [115:32] expressions directly in the print [115:35] function. So that's it for this video [115:38] guys. Thank you very much for watching. [115:39] In this section we will explore if [115:42] statements or conditions and how to use [115:44] them. If statements are also known as [115:47] conditional statements or decision [115:49] making statements. They are extremely [115:52] important in all programming languages. [115:55] So far we have been writing simple [115:57] scripts line by line. Now to make our [116:00] programs a bit smarter, we will use if [116:03] statements to add conditional logic and [116:06] make our code more intelligent and [116:09] powerful. Conditional statements allow [116:11] programs to make decisions based on the [116:15] conditions you define. Suppose you want [116:18] your program to compare two numbers and [116:21] determine which is bigger. For us, this [116:24] is effortless. We can look at the [116:26] numbers and instantly know which is [116:29] bigger, right? However, computers do not [116:32] understand anything automatically. You [116:35] must explicitly program every single [116:38] decision. No matter how small even [116:41] something like as basic as comparing two [116:43] numbers whether it is a simple task like [116:46] this or a complex operation you need to [116:50] define all possible scenarios in code. [116:53] This is what if statements solve. They [116:56] enable programs to compare values [116:59] whether numbers, strings or other data [117:02] types and make decisions based on [117:05] defined conditions. Now let's dive into [117:07] the practicals. Write if the if keyword [117:10] is used to create if conditions or the [117:14] if statements after if space is very [117:18] important. Now write the condition that [117:20] you want to test. Let's say 45 greater [117:24] than six. The greater than sign is [117:26] called the relational operator. It [117:29] checks if the value on the left side is [117:32] greater than from the value on the right [117:35] side. Now the way the if statements work [117:39] is Python checks if the specified [117:43] condition is true or false. If the [117:46] condition is true, then Python is going [117:49] to execute the code that belongs to this [117:53] if statement. Now every if condition has [117:57] its own block. In that block we define [118:00] or write the code that will be executed [118:04] if the condition is evaluated to. Next [118:07] step is to write the code that will be [118:10] executed when this condition is true. So [118:13] write colon. Colon is important. It [118:16] basically tells Python that this [118:18] expression ends here. After this the [118:21] block or body of uh this if statement [118:24] starts. Now how does Python uh recognize [118:27] or identify body of of a control [118:31] structure like uh this if statement? [118:34] Well, it uses something called the [118:37] indentation. Indentation is nothing but [118:40] the spaces that you add at the beginning [118:43] of a line. Let me show it to you. Press [118:46] enter. As you can see here, Python has [118:49] automatically inserted four spaces, [118:52] right? Let me go back to the if [118:54] condition. Press enter. As you can see, [118:56] it automatically inserted four spaces. [118:59] This is the indentation. And for some [119:02] reasons, if your code editor is not [119:06] inserting spaces automatically, then you [119:09] need to add them manually. So add four [119:12] spaces manually like this. 1 2 3 four. [119:16] Most of the code editors will [119:18] automatically insert four spaces. Now [119:21] these spaces are called the indentation. [119:24] The code that you write with the same [119:27] level of indentation, that code will [119:30] exclusively belong to this if statement. [119:33] I will break down this in a minute. For [119:35] now let me write [119:40] condition true 45 is [119:45] so the way if statements work is Python [119:48] first evaluates or checks this [119:51] condition. If this condition is true or [119:54] false. If the condition is true then it [119:58] will execute the body or block of this [120:01] statement which is defined using the [120:04] indentation. [120:06] Now since this condition is true, Python [120:09] will execute this print statement. [120:11] Obviously this condition is true, right? [120:13] 45 is greater than six. So it will [120:16] execute the this line which is written [120:19] inside the block of this if statement. [120:22] Let's uh execute the code. And we have [120:25] the expected output. It has printed this [120:28] line. Now let me write another print [120:32] statement to uh demonstrate the [120:35] indentation. The concept of indentation [120:38] inside the [120:40] statement. Now the code that you write [120:43] with the same level of indentation that [120:46] code exclusively belongs to the if [120:49] statement or this if statement. Now as [120:52] you can see here both of these lines are [120:55] using the same level of indentation. The [120:59] indentation is determined by the first [121:02] line that you write immediately after [121:06] the if statement. Now first line is [121:08] using four spaces as indentation. Right? [121:11] Now all the subsequent or lines after [121:15] the first line must also use the same [121:18] level of indentation. Then those lines [121:21] will belong to the if statement. This [121:24] time since these two lines are using the [121:27] same level of indentation, these two [121:29] lines exclusively belong to this if [121:32] statement. So if this condition is [121:35] evaluated to true, these two lines will [121:38] be executed. [121:40] As you can see this time we have this [121:43] output. This condition was evaluated to [121:45] true. And since these two lines belong [121:48] to this if statement they were executed. [121:52] Let me write another line print [121:57] true. Now we have these three lines that [122:00] are using the same level of indentation [122:03] and they belong to this if statement. So [122:06] if this condition is evaluated to true, [122:08] these three lines will be executed. As [122:11] you can see now indentation doesn't [122:14] always uh has to be four spaces. You can [122:18] customize it to your liking. The four [122:22] spaces is basically the standard and [122:25] default indentation. You can use one, [122:30] two or eight spaces, however many you [122:33] like. Now like I like I said earlier the [122:36] indentation is determined by the first [122:40] line that you write immediately after [122:42] the if condition. If first line uses one [122:45] space as as an indentation then rest of [122:49] the lines must follow the same level of [122:51] indentation. This time the first line is [122:54] using one space as as an indentation but [122:58] uh remaining two lines are not. So let's [123:01] see what output we get. We have the [123:04] error. Now check out the error. [123:06] Indentation error means we don't have a [123:09] consistent indentation. But if I use the [123:14] same level of indentation, now it will [123:18] fix the error. As you can see, now we [123:21] have the expected output. These three [123:24] lines belong to this if statement, [123:26] right? they were executed when Python [123:29] evaluated this condition to true. Four [123:33] spaces is the default indentation. So [123:36] indentation is important. It will be [123:38] used a lot as we progress in this [123:41] course. Indentation will be used with [123:43] functions, loops and many more control [123:46] structures. I hope that indentation is [123:49] clear. Now let's move on to the else [123:52] statement. The if statement offers two [123:56] possibilities or two possible outcomes. [124:00] We can have uh one outcome for true and [124:03] other outcome for false. Right? Now here [124:06] Python is going to execute the block of [124:09] if this condition is evaluated to true. [124:12] Right? But what happens if the condition [124:14] is false? Let's say 45 greater than 69. [124:19] Here condition is false. Right? 45 is [124:22] not greater than 69. Since this [124:25] condition is false, the body of if will [124:28] not be executed. The body of an if [124:31] statement is only executed when [124:33] condition is true. As you can see this [124:36] time we have no output because the body [124:38] of if is only executed when condition is [124:42] true. Now what we are going to do is [124:44] write the code for the false condition. [124:48] So else write else colon just like the [124:51] if statement else [124:54] also has its own block or body that body [124:58] gets executed when condition is false. [125:01] Now this time we have false as as an [125:04] output because the else only gets [125:07] executed when the condition is false. [125:10] Okay. So here if condition is true block [125:13] of if gets executed and if the condition [125:16] is false the block of else gets [125:19] executed. Make sure to write the else [125:22] outside of the block of if that is [125:25] important. Okay so else is basically [125:28] kind of a backup right? If the condition [125:32] is true then block of if gets executed [125:35] but if the condition is false then block [125:38] of else gets executed. Just like the if [125:42] statement else also has its own block [125:45] which is defined by the indentation. [125:50] Print inside [125:54] else block. [125:56] This time we have these two lines of [125:59] output because the block of else was [126:01] executed. So these two lines were [126:04] executed. Both of these lines use the [126:07] same level of indentation. Right? Now [126:10] let's dig a bit deeper into into the if [126:14] statement. How actually things work in [126:17] the background. So what I'm going to do [126:19] is uh take this exact expression and put [126:23] it in the print statement. Uh let's [126:27] execute the code. As you can see we have [126:31] false. This is output of this print [126:33] statement is false. Now we are using the [126:37] same expression in the if statement. So [126:40] the way Python works is first it [126:43] evaluates this expression then based on [126:46] the output of this evaluation then it [126:50] makes a decision. Now here output of [126:53] this expression is false. So if it is [126:56] false then the block of else gets [126:59] executed but if it is true [127:05] then block of if gets executed. As you [127:08] can see this time true output of this [127:11] expression was true right so when an [127:15] expression is evaluated to true the [127:18] block of if gets executed that's how it [127:21] works I hope it is clear and before [127:24] signing of instead of using uh values we [127:29] can also use variables like this a equal [127:32] to this bal [127:35] now replace values with variable ables. [127:38] Now here everything remains same except [127:41] for the variables right here I'm [127:44] providing the if statement variables a [127:47] greater than b variable a is storing 67 [127:51] b is storing five so it checks if value [127:54] assigned to a which is 67 is greater [127:57] than five so based on the values it [128:00] makes a decision now we also have other [128:04] relational operators like less than [128:07] Right? So less than operator checks if [128:10] the value on the left side is lesser [128:13] than value on the right side. As you can [128:17] see false because 67 is not less than [128:21] five. We also have less than greater [128:25] than equal to. Now greater than equal to [128:28] is basically combination of two things [128:31] greater than and equal to. Let's uh make [128:34] both values same. 67 [128:43] and let's execute this code. We have [128:46] false. So here I'm checking if A is [128:50] bigger than B. Now value of A is 67 and [128:55] value of B is 67 as well. So obviously [128:59] it is checking if 67 is greater than 67. [129:03] Condition is false. 67 is not greater [129:07] than 67. It is equal to 67. So condition [129:10] was evaluated to false. The block of [129:13] else was executed where we printed [129:16] false. Now what happens if you use [129:20] greater than and equal to relational [129:22] operator. It is combination of two [129:25] things greater than and equal to. So [129:28] this time first let's execute the code. [129:30] We have the [129:33] output. Let me reexecute it. We have the [129:36] output true. Now here Python checks for [129:40] two things. First it checks if a is [129:44] greater than b. Then it checks if a is [129:48] equal to b. So in first case when it [129:52] checks if a is greater than b condition [129:55] is false. 67 is not greater than 67 then [129:59] we are also using greater than equal to. [130:02] Then it checks if a is equal to b [130:05] condition is true. A indeed is equal to [130:08] b. So this expression is evaluated as [130:12] true. So we are printing true as you can [130:16] see. So greater than equal to basically [130:18] checks if the value is either greater [130:21] than or equal to. We also have less than [130:24] equal to. It also works the same as [130:27] greater than equal to. So that's it for [130:29] this video. In this video, we will take [130:31] a look at the else if statement which is [130:34] written as l if in Python. It's used [130:37] when you want to check multiple [130:39] conditions sequentially, not just a [130:42] single one. In our previous video, we [130:44] covered the basic if else statement. [130:48] With if else, you only have two possible [130:51] outcomes. If the condition is true, the [130:55] if block gets executed. If it is false, [130:58] the else block gets executed, right? It [131:01] gives us only two possibilities. [131:04] However, in most real world [131:06] applications, you need to check for more [131:09] than just two possibilities. In such [131:11] cases, Python provides the else if [131:14] statement, which allows us to check [131:17] multiple conditions and handle different [131:20] scenarios one after another. Now, let's [131:23] dive into the practicals. We are going [131:25] to write a program to determine grade of [131:29] a student based on their score. Let's [131:32] say we have four possible grades A B C D [131:37] and if a student scores let's say 90 and [131:41] above they get grade A. If they score 80 [131:44] or above they get B and so on. Now the [131:49] simple if statement is not enough for [131:53] writing such programs because it only [131:56] gives us two possibilities. We need [131:59] something more complex that that can [132:02] check for all the four possibilities. [132:05] That's where we use the else if [132:09] statements. So let's create a variable [132:11] score equal to uh 74. [132:16] Now write if [132:18] score is greater than [132:22] 90 then [132:25] print. [132:29] Make sure that there is uh the [132:31] indentation as we discussed in the [132:33] previous video. Now write else if. Else [132:39] if is written as l if in Python. L if [132:43] basically means else if. That's the [132:45] keyword to write the else if statements. [132:58] Else if [133:00] core greater than 70 [133:05] print [133:07] grade [133:09] else if score greater than uh 6 and [133:14] sometimes uh my code editor doesn't add [133:18] the indentation. So make sure to add [133:20] indentation [133:22] manually. print [133:25] C-grade. [133:29] Now at the end we must write the else [133:32] statement. Else is always defined at the [133:36] end. Print Dgrade. [133:42] Now let me execute the code then I'll [133:44] break down everything. And we have the [133:47] output C grade. So here I have created [133:51] the variable score and assigned it the [133:54] value 74. Now the way the else if [133:57] statements work is the conditions are [134:00] checked sequentially from top to bottom. [134:03] So first uh Python is going to check if [134:06] score which is 70 is greater than 90 [134:10] condition is false. 74 is not greater [134:13] than 90. So it will not execute the [134:17] block of this if statement. Now Python [134:20] automatically moves to the next [134:23] statement which is this else if [134:25] statement. Here we are checking if score [134:27] is greater than 80. This time also [134:31] condition is false. 74 is not greater [134:34] than 80. Just like the if statements, [134:37] all else if statements have their own [134:41] blocks and blocks are defined using the [134:44] indentation. Just like the if statement. [134:47] Now since this condition is false, [134:49] Python moves to the next else if [134:52] statement which is this. Here we are [134:54] checking if 74 is greater than 70. This [134:58] time condition is true, right? 74 is [135:01] greater than 70. Now if an if condition [135:04] or an else- if condition is evaluated to [135:07] true block of that condition gets [135:10] executed since this condition is [135:12] evaluated to true block of this gets [135:15] executed where we are printing this line [135:18] C grade that's why we have the output C [135:22] grade now when a condition is evaluated [135:25] to true Python does not check rest of [135:28] the else if statements so as soon as [135:31] this condition is evaluated ated to [135:33] true. It will not check rest of the else [135:36] if statements. The code will exit out of [135:39] this structure and continue executing [135:43] code that is written after this [135:45] structure. In the multiple else if [135:48] statements, the code is checked [135:51] sequentially from top. Okay. Now let's [135:54] modify this score. [135:58] Let's say 93. [136:01] Congrats, you have earned a grade [136:04] because here Python checks if score [136:07] which is 60 93 is greater than 90 [136:10] condition is true. So block of if was [136:13] executed [136:14] uh let's say 67 we should have C grade [136:20] as you can see. Now what is role of this [136:24] else statement here? Well, in else if [136:27] statements, the else block is executed [136:31] only when none of the conditions are [136:34] true. So here, let's make uh this all [136:38] the conditions false. So let's say score [136:40] is 44. [136:44] Now we have degrade which is part of the [136:47] else block. Why? Because none of the [136:50] conditions were true. So here Python [136:52] checks if 44 is greater than 9 0 [136:55] condition is false. Here it checks if 44 [136:58] is greater than 80 condition is false. [137:00] Here also condition is false. Condition [137:03] is false because 44 is not greater [137:06] greater than 60 since none of the [137:09] conditions matched the block of else was [137:13] executed. Right? Degrade. So else is [137:16] only executed when none of the [137:19] conditions match or when none of the [137:22] conditions are true. That's how else if [137:27] statements work. I hope guys this is [137:29] clear. Now in this quick video we will [137:31] learn about the equality operators in [137:34] Python. Equality operators are used to [137:37] compare values or data to check whether [137:40] they are equal or not. There are two [137:44] primary equality operators in Python. [137:47] Equal to and not equal to. These [137:49] operators return a boolean value. They [137:52] return true if the condition is [137:54] satisfied or met and false if it is not. [137:59] Now let's dive into the practicals. So [138:02] write if 34 equal to. Now here this is a [138:07] simple if statement, right? where I'm [138:10] checking if 34 is equal to 34. Let me [138:14] finish the code then I will break down [138:16] this code. Yes, both are equal. [138:21] Equal [138:23] and we have the expected output both are [138:26] equal. Now as you can notice here to [138:29] compare values I have used two equal to [138:33] signs. So to compare two values we need [138:37] to use two equal to signs. This is [138:39] called the equality operator because one [138:43] equal to sign as you can see here it is [138:46] used to assign data to a variable. [138:49] Right? So to compare two values we need [138:52] to use two equal to signs which is [138:55] called the equality operator. It checks [138:58] if two provided values are equal or not. [139:02] Uh let's write else as well. [139:05] R [139:07] not equal. [139:09] So here Python checks if 34 is equal to [139:13] 34. Condition is true, right? 34 is [139:16] indeed equal to 34. So block of if gets [139:20] executed, right? Yes, both are equal. [139:24] Now let's make it uh 314. [139:29] This time we have the output not equal. [139:32] So here these two values are not equal. [139:36] The equality operator only returns true [139:40] if both the values are equal. This time [139:43] 34 is not equal to 314. Right? So the [139:46] condition was evaluated to false. That's [139:50] why the block of else was executed where [139:53] we are printing this statement. Not. Now [139:56] we can also use uh sorry compare [140:00] strings. [140:02] Now let me get rid of this [140:05] root. When you want to compare strings, [140:08] strings must always be surrounded within [140:11] quotes. So like this root now here I'm [140:15] checking if root is equal to root [140:18] condition is true because [140:21] they are equal values. What happens if I [140:23] add space [140:26] not equal? So spaces also get counted. [140:31] Now here Python is checking if root is [140:34] equal to root plus space. So these [140:38] values are not equal. So remove the [140:40] space and now these values are equal. [140:44] Let's compare if root is equal to root [140:47] one. Okay, not equal. Obviously root is [140:51] not equal to root one. So that's how the [140:54] equality operator works which is [140:57] represented by two equal to signs. Now [141:00] another equality operator that we have [141:03] is called the not equal to operator. The [141:07] not equal to operator checks if the [141:10] provided values are not equal. So if 12 [141:14] is not equal to 8, [141:18] print [141:21] not equal [141:25] else. [141:28] The way it works is if the values [141:30] provided here are not equal. If they are [141:33] not equal, the condition is evaluated to [141:37] true. Now here I'm basically checking if [141:40] 12 is not equal to 8. condition is [141:42] obviously true. It is not equal to 8. So [141:45] block of if will be executed. As you can [141:49] see not equal. Now what if I check if 12 [141:54] is not equal to 12 [141:57] and we have equal because these two [142:00] values are equal. So when the values are [142:03] equal the block of else gets executed [142:07] because when values are equal the [142:09] condition is evaluated to false. That's [142:12] why we have the else block being [142:14] executed. But when the values are not [142:17] equal then the condition is evaluated to [142:21] true and block of if gets executed. So [142:26] that's the syntax to write the not equal [142:28] to operator. We have to write the [142:30] exclamation mark then equal to sign. You [142:34] can also add spaces like this. [142:38] It is also fine as you can see not [142:42] equal. In this video we are going to [142:44] cover the different types of logical [142:47] operators in Python. There are three [142:50] main types of logical operators and or [142:54] and not. These are most commonly used [142:57] with if conditions or statements. [143:00] Logical operators allow us to combine [143:02] two or more conditions into a single [143:05] expression which enables us to perform [143:08] operations based on multiple conditions. [143:10] In simpler terms, they let you check [143:13] multiple conditions within a single if [143:15] statement. The result of a logical [143:18] expression is always either true or [143:21] false. There are three main types of [143:24] logical operators in Python. And, or, [143:28] and not. Let's start with the and [143:31] operator. The and operator checks two or [143:34] more expressions or conditions. You must [143:37] provide it at least two conditions for [143:40] it to work. Let's uh jump into the [143:43] practicals. We are going to start with [143:45] the and operator. We are going to start [143:48] with a simple example. So write if uh [143:52] let's say 44 equal to 44 [143:56] space. Now write and the and operator is [143:58] represented by the and keyword in Python [144:03] space. Now specify the second condition [144:06] 55 is equal to 55 colon in the block of [144:11] if statement we are going to print true [144:16] all values are uh same or equal. [144:21] Now let's break uh this down. The way [144:24] the and operator works is it needs [144:27] minimum two conditions or expressions to [144:32] work. Right? So here we have correctly [144:34] provided two conditions and second the [144:37] most importantly and operator returns [144:40] true if all the specified conditions are [144:44] true. If all the conditions are true [144:47] then that if statement is evaluated as [144:51] true. Right here we have two conditions. [144:54] The first condition says if 44 is equal [144:57] to 44 condition is obviously true and [145:00] the second condition says if 55 is equal [145:03] to 55. Now both of these conditions are [145:06] true. So when all the conditions are [145:09] true that if statement is evaluated as [145:12] true and the block of if gets executed. [145:16] Let's execute the code and the block of [145:18] if has been executed. Right? So that's [145:21] how the and uh operator works. It allows [145:25] us to combine multiple conditions into [145:29] one single expression. Now let's combine [145:33] one more condition and 66 equal to 66. [145:38] This time we have provided three [145:40] conditions and all the three conditions [145:42] are true. Right? Since all the [145:45] conditions are true, this if statement [145:48] will be evaluated as true. Now what [145:52] happens if a condition is false? Let's [145:54] say 66 is equal to 61. [145:58] Let's execute the code. And this time we [146:01] have no output because the way and [146:04] operator works is it returns true only [146:08] if all the conditions are true. But here [146:12] uh one condition is false. So when even [146:16] one condition among all the provided [146:18] conditions is false then the and [146:21] operator returns false and that if [146:24] statement is then evaluated as false. [146:28] Therefore the block of if will not be [146:30] executed. Let's specify [146:34] the else block. [146:37] Print false. [146:39] Now this time we have the false in the [146:42] output because we have one condition [146:44] which is false. So this expression was [146:48] evaluated as false. Like I was saying, [146:52] you can combine as many conditions as [146:54] you like using the and logical operator. [146:58] It allows us to combine multiple [147:01] conditions into a single expression. [147:03] Here we have four conditions and since [147:06] all the four conditions are true, the [147:10] block of if has been executed. To [147:12] summarize the logical and operator, it [147:16] needs minimum two or more expressions or [147:20] conditions to function and it returns [147:23] true only if all the provided conditions [147:26] are true. Now let's move on to the or [147:29] operator. The logical or operator is [147:33] similar uh to the end operator but at [147:37] fundamental level it works slightly [147:40] differently. So uh let's say if 22 equal [147:43] to 22 the or operator is represented by [147:48] the or keyword space 1 = 1 print [147:56] true [147:58] else [148:00] print [148:02] false. Now the way or operator works is [148:05] just like the and operator. It needs [148:08] minimum two conditions to work. We have [148:11] provided two conditions and it returns [148:15] true even if one condition is true. Here [148:20] we have provided two conditions. Both [148:22] the conditions are true. So it will [148:24] return true as you can see. [148:27] Now let me specify [148:30] a false condition. As you can see, first [148:32] two conditions are true, but the third [148:34] condition is false. It will still return [148:37] true because it only needs one condition [148:40] to be true. Then it returns true. Now it [148:44] returns false only if all the conditions [148:48] are false. [148:52] This time I have provided three [148:54] conditions, right? And all of these are [148:58] false. So when all the conditions are [149:01] false then it returns false. Therefore [149:04] the if statement will be evaluated as [149:08] false as you can see. Okay. Now let's [149:10] make one condition true. Now here since [149:15] at least one condition is true it will [149:17] return true. Okay. So to summarize the [149:21] logical or operator needs only one [149:24] condition true then it returns true. It [149:28] returns false only if all the provided [149:31] conditions are false. Just like the and [149:34] operator, it needs minimum two or more [149:38] conditions. Okay, this way you can [149:40] combine as many conditions as you like [149:44] with the logical or operator. Now the [149:47] third logical operator that we have is [149:51] not operator. Now the way not operator [149:54] works is it basically flips or changes a [149:59] condition. If a condition is true, it [150:02] makes it false. If a condition is false, [150:05] then it makes that condition true. Let [150:08] me show you. If 34 is equal to 34, [150:12] sorry, uh 34, [150:16] print [150:19] true. [150:20] else we are going to write false. [150:29] As you can see we have true in the [150:30] output. Here I'm checking a simple [150:33] condition if 34 is equal to 34. [150:36] Obviously condition is true. 34 is equal [150:39] to 34. So block of if gets executed. Now [150:43] the not operator is represented by the [150:46] not keyword. So write not space. [150:51] Now we have false in the output. Right? [150:55] This is because the way it works is [150:58] first Python evaluates this expression [151:02] 34 is equal to 34. Condition is true. So [151:05] it returns true. Since we are using the [151:08] not operator. Not operator takes the [151:11] result of this expression then changes [151:14] it to false. not operator makes it [151:18] false. Now once it is evaluated as [151:20] false, it will not execute the block of [151:23] if it will execute the block of else. [151:26] That's why we have false in the output. [151:28] That's how the not operator works. It [151:31] changes true to false and false to true. [151:34] Now let's make it false. As you can see [151:36] we have this time true. So here first [151:39] Python evaluates this condition 34= to [151:42] 341. condition is obviously false. Now [151:47] the not operator takes the result makes [151:50] the false into true or changes the false [151:53] into true. Once it is evaluated as true [151:57] the block of if gets executed where we [152:00] have printed this true right so that's [152:04] how guys the not operator works. uh we [152:06] will continue from where we left off in [152:08] the previous video where we learned the [152:11] fundamentals and basic working of [152:14] logical operators. Now we will move on [152:16] to something more complex to understand [152:18] them more deeply. We will dive deeper [152:21] into logical operators specifically the [152:24] and and or operators. Both of these [152:27] operators have many practical uses. For [152:31] example, it is useful when multiple [152:33] conditions must be true simultaneously, [152:36] such as validating whether both a [152:38] username and password are correct. We [152:41] will create a simple dummy program to [152:44] check whether the username and password [152:47] entered by the user are correct or not. [152:51] Now let's dive into the practicals. I'm [152:54] going to create a basic authentication [152:57] script that will check if the username [153:00] and password that the user enters are [153:03] correct or not. So [153:07] uh let me create variable username. The [153:10] correct username is going to be root and [153:14] the correct password is going to be [153:20] admin. So if user enters username root [153:23] and password admin then uh it will be [153:26] authenticated and if user enters [153:28] anything apart from these two then the [153:31] script or authentication will fail. So [153:34] first thing that uh we need to do is [153:36] obviously ask the user for inputs. So [153:40] name equal to input [153:44] enter the username [153:48] and add space after the greater than [153:50] sign [153:52] password equal to make sure that you [153:55] have a different variable name for this [153:57] password. Okay. If you uh give the same [154:00] variable names for both of these uh [154:03] variables then uh this variable is going [154:05] to override the the value of this [154:09] variable where we have stored the actual [154:12] password. Password equal to [154:16] input [154:19] enter the password. [154:23] So let's compare. So, so the logic is [154:27] going to be we are going to compare the [154:29] username and password that user enters [154:32] with the username and passwords that we [154:35] have stored in these variables. So name [154:39] the name this name variable as you can [154:41] see it stores whatever user enters as [154:44] username if uh it is equal to username [154:49] that we have stored in this username [154:52] variable [154:53] username. Now, and the and operator as [154:57] we saw in the previous video, it allows [154:59] us to combine multiple conditions. And [155:03] we are going to check password as well. [155:06] If the password, let me copy the exact [155:09] variable. If the password that user [155:12] enters is equal to the password that we [155:14] have stored in the variable here, [155:19] print [155:21] authentication. Authentication [155:25] successful [155:30] else sorry else [155:34] print [155:36] wrong username or password [155:42] password so let's execute the script [155:44] then I will break down everything enter [155:47] username first we are going to start uh [155:49] by uh by entering the incorrect username [155:53] and password. Password [155:56] as you can see wrong username and [155:58] password. Now let's enter the correct [156:01] username which is root. [156:05] Password is admin. The correct password [156:07] is admin. Press enter. As you can see [156:10] authentication successful. Here I am [156:13] asking user to enter a username and [156:16] password. Username gets stored in the [156:18] name variable. password gets stored in [156:20] the password variable. Here I'm checking [156:23] if the username that user enters is [156:26] equal to the variable username which is [156:28] storing the correct username root. Then [156:31] we are using the end operator. Here we [156:33] are checking if password is equal to [156:36] password that user enters. Right? This [156:39] variable is storing whatever password [156:41] user enters against the password that we [156:44] have stored in this variable. Now the [156:48] way the on and operator works is both of [156:51] the conditions must be true. So user [156:53] must enter the correct username and [156:57] password then both of these conditions [157:00] will match or will be evaluated to true. [157:04] Therefore this if statement will be [157:06] evaluated as true and the block of if [157:10] will be executed. If the user enters [157:13] either a username or password wrong, [157:16] then this condition will be evaluated as [157:19] false and the block of else will be [157:22] executed. Right? So this is a very [157:24] simple yet very useful when it comes to [157:26] understanding the working of the end [157:29] operator in real world. So that's the [157:32] that's how the end operator works. So [157:35] let me know if you have any questions [157:37] regarding this. I'll happily answer [157:39] everything. Now let's uh uh do one [157:42] example for the or operator as well. So [157:45] what I'm going to do is I will check if [157:48] a character is consonant or vowel vowel [157:52] right vowel characters are these right a [157:55] i e o and u I'm going to ask user to [158:01] enter a character then based on the [158:04] entered character we will tell whether [158:07] it is um a vowel or consonant okay these [158:10] are vowel and rest of the characters are [158:13] consonant So first let's enter a [158:17] character input. [158:20] Enter a character. [158:24] Now I'm going to check if the character [158:26] is wow or not using the or operator. So [158:31] if the care the care variable is storing [158:34] whatever character user inputs. If care [158:37] equal to I or if care equal to E or care [158:46] equal to O or if care uh equal to U [158:55] or if care equal to A, [159:01] it is a vowel. else [159:06] print it is a consonant [159:09] it is a consonant. Now if you remember [159:12] the way the or operator works is it only [159:16] needs one condition to be true. Then [159:18] that if statement is evaluated as true [159:21] right? So here I'm asking user to enter [159:24] a character. So whatever character user [159:26] enters that gets stored in the care [159:29] variable. So if user enters uh let's uh [159:33] execute code I it is a vowel right a it [159:38] is a vowel now let's enter a consonant [159:41] it is a consonant here in the if [159:44] condition I'm checking for all the five [159:48] possible vowels right so if user enters [159:52] any of the five wow then this if [159:55] condition will be evaluated as true [159:58] because we are using or. So the or [160:00] operator needs only one condition to be [160:04] true. Then uh that if statement is [160:06] evaluated as true. For example, [160:10] let's enter E. It is a vowel. So E that [160:14] I entered got stored in the care. So I [160:17] am checking if care whose current value [160:20] is E is equal to I. Condition is false. [160:23] Now here care which is E is equal to E. [160:28] So since the values ma matched the if [160:31] statement was uh evaluated as true and [160:34] block of this if statement was executed. [160:37] So yeah that that's how you can use the [160:39] or operator. Okay let me demonstrate the [160:42] consonant uh as well [160:45] K as you can see it is a consonant. So [160:48] the value of care is K. So here it is [160:52] checking if the K is equal to I [160:55] condition is false. If k is equal to a [160:58] condition is false. If care or k is [161:00] equal to o condition is false. If care [161:03] is equal to u condition is false. If the [161:06] care which is k is equal to a condition [161:09] is false as well. So here none of the [161:12] conditions matched. Since none of the [161:15] conditions matched the or operator [161:18] returned false therefore this condition [161:20] was evaluated as false and the block of [161:23] else was executed. So that's it for this [161:26] video guys. In this section we will be [161:28] learning about loops in Python. Loops [161:31] are one of the core components in any [161:33] programming language. A loop allows us [161:35] to automate repetitive tasks and help us [161:38] avoid writing the same code over and [161:41] over again. For example, if you want to [161:44] print hello world 10 times or display [161:46] numbers from 1 to 100 without a loop, [161:50] you would have to write 10 separate [161:52] lines of code just to print hello world [161:55] 10 times. Now imagine having to print it [161:58] 100 times. That would be a big problem, [162:02] right? It is not only time consuming but [162:04] also inefficient and completely [162:07] impractical in real world. That's where [162:10] loop comes in. With a loop, we can [162:12] automate such repetitive tasks and get [162:16] the same result with just a few lines of [162:20] code. That's the power of loops. Loops [162:23] automate repetitive tasks by executing a [162:26] block of code multiple times or as long [162:29] as the condition remains true. A loop [162:32] has a block of code similar to if [162:34] statement. block of loop is executed [162:37] repeatedly as long as a specified [162:39] condition remains true. Now let's dive [162:43] into the practicals. So write for the [162:45] for keyword is used to create a for loop [162:48] in Python space. Now write I. Now this I [162:52] is a variable. This is this for loops [162:55] variable space. Write in range. I will [162:59] write the complete code then break down [163:01] everything. Now parenthesis. Now inside [163:04] the parenthesis of the range function we [163:06] need to specify three values. The first [163:10] value is going to be start value where [163:14] the loop or sequence starts. So this [163:17] loop is going to start from 1, the [163:21] second value is going to be the ending [163:23] value. How long this loop will run 12. [163:27] So this loop or sequence starts from 1 [163:30] and ends at 12, the third value is going [163:34] to be the increment. After each [163:37] iteration, this loop will be incremented [163:39] by one. I know for now it is a bit [163:42] confusing but it will get crystal clear [163:44] in next few minutes. Now colon after the [163:48] colon the block of for loop starts just [163:52] like an if statement has its own block [163:55] or body. Uh similarly a for loop also [163:58] has its own body. Python keeps executing [164:01] the code that you write inside the body [164:04] of for loop as long as uh the condition [164:08] remains true. Press enter. As you can [164:10] see, it has automatically inserted four [164:13] spaces. The block of a for loop is [164:17] defined by the indentation. This is the [164:19] indentation, right? Just like the if [164:22] statement. And for some reasons if your [164:26] code editor doesn't add indentation [164:28] automatically then you can insert four [164:31] spaces manually like this 1 2 3 4. Four [164:35] spaces are the default indentation to [164:37] define the for loops block or block of [164:40] any control structure in Python. Now in [164:44] the block of for loop I'm going to print [164:47] the value of I. What is I? I is this for [164:51] loops variable. So write that here. [164:53] Let's execute the code. We have the [164:55] output. We have numbers being printed [164:58] from 1 to 11. So let's break down this [165:01] output. So this loop starts from 1. This [165:06] is the starting value. So when this loop [165:09] runs for the first time, the value of i [165:12] is initialized to one. the value of i [165:15] becomes one because here I have [165:18] explicitly told the range function that [165:21] this loop starts from one. Now after [165:25] giving the i variable uh its initial [165:28] value now python checks if the current [165:32] value of i is less than the second value [165:35] that you provide here which is 12. So in [165:38] the background, Python basically checks [165:41] if the current value of I which is 1 is [165:45] less than the value that you specify [165:47] here which is 12. Condition is true. [165:50] Right? Current value of I is uh 1. I is [165:54] less than 12. Now as soon as the [165:57] condition is evaluated to true, the [166:00] Python executes the code that you have [166:03] written inside the block of for loop. So [166:06] inside the block of for loop I am [166:08] printing I. So Python prints I. The [166:11] current value of I is one. So Python [166:13] prints one. Right? Now since we don't [166:16] have any lines of codes inside the block [166:19] of this for loop, control moves back to [166:22] the for loops structure. Now Python [166:25] executes this third part of this for [166:28] loop which is one. This is called the [166:30] increment value. Now, Python will [166:33] increment the value of I by 1 or [166:37] whatever value you put in here. So, [166:39] current value of I is 1, right? So, in [166:43] the background, it simply does this. The [166:45] current value of I is 1. So, 1 + 1 [166:50] becomes 2. Now, Python updates the value [166:53] of I with two. Now, the value of I [166:57] becomes two. The old value which was 1 [166:59] is replaced by the new updated value [167:02] which is two. Now Python compares if two [167:06] is less than the value specified here 12 [167:10] condition is true. Now Python executes [167:13] its block in the block it prints value [167:16] of i which is two. So it prints two. Now [167:19] control goes back to the for loop again. [167:21] It increments the value of i by one. The [167:25] current value of I is 2. So 2 + 1 [167:28] becomes 3. Now the value of I is 3 and [167:31] it checks if 3 is less than 12. [167:34] Condition is true. Then it prints three. [167:37] Now Python keeps executing block of for [167:40] loop. As long as the condition remains [167:44] true. Now when the value of i becomes [167:47] 12, Python checks if the 12 is less than [167:51] 12. This time condition is false. 12 is [167:54] not less than 12. It is equal to 12. So [167:58] as soon as the condition is evaluated to [168:00] false, Python will not execute the block [168:04] of for loop. The loop terminates right [168:08] here. As soon as condition is evaluated [168:10] to false, the loop terminates here. The [168:13] control moves out of the for loops [168:15] structure. That's why we have numbers [168:17] being printed up to 11. in the range [168:20] when you specify the second number, [168:23] Python doesn't include that number. So [168:26] in the background, Python does something [168:28] like this. Whatever number you specify [168:31] minus one. So Python generates sequence [168:35] from 1 to number that you specify here [168:38] minus one. [168:41] So that's how guys the for loop works. [168:45] Now let's say I want to print hello [168:47] world 10 times. Just write hello world. [168:54] As you can see now it has printed the [168:58] hello world 11 times because loop starts [169:00] from one and it keeps running as long as [169:04] the value of i remains less than 12. So [169:06] 1 to 11. So it has printed the hello [169:10] world 11 times. Now the reason it has [169:13] printed uh the hello world 11 times [169:15] because this block of for loop gets [169:19] executed 11 times. When this loop runs [169:22] for the first time, value of i is one. [169:24] So python checks if i is less than 12. [169:29] Condition is true. So it executes the [169:31] hello world for the first time. Now [169:33] control goes back to the for loop. Value [169:36] of i becomes 2. It checks if 2 is less [169:39] than 12. condition is true. Now it [169:43] executes the block of uh for for the [169:46] second time. So it prints hello world [169:49] for the second time. So it keeps [169:50] executing the block of uh for loop as as [169:54] long as the condition remains true. Now [169:57] let's uh print I alongside hello world. [170:01] As you can see now we are printing hello [170:04] world alongside the value of i. Right? [170:10] print. Let's write one more [170:14] uh print statement for loop [170:18] at work. [170:22] Now this time in the block of for loop [170:25] we have two print statements. So on each [170:29] run Python is going to execute these two [170:32] lines as long as this loop keeps [170:36] running. Right now, just like the if [170:38] statements, the block of for loop is [170:41] determined by the first line that you [170:44] immediately write after the for loop. [170:47] Since first line is using four spaces as [170:50] indentation, rest of the lines in the [170:53] block of for loop must also follow the [170:56] same level of indentation. Then they [170:58] will be considered part of that for [171:00] loop's body or block. [171:04] So guys, that's how the for loop works. [171:07] We are going to continue where we left [171:09] off in the previous video. In this [171:11] video, we will uh explore the for loop [171:15] in a bit more detail. In the previous [171:18] video, we just understood the working of [171:21] of the for loop. Right? So write for i [171:26] in range. [171:30] This loop uh will print numbers from 1 [171:34] to [171:36] to 11. So I this is for loops variable. [171:40] So let's uh execute the code. We have [171:42] the numbers being printed from 1 to uh 1 [171:46] to 11. Right? This range function [171:49] generates the sequence from 1 to 12 - 1. [171:53] So number that you specify here, the [171:55] loop runs up to that number minus one. [171:58] Right? That's how it works in the in the [172:01] background. So when this loop runs for [172:04] the first time, the value of I becomes [172:06] one. It is initialized to one. Right? So [172:10] the role of in keyword is that uh it [172:13] takes the value that the range function [172:16] generates then put that in the I [172:18] variable. So when this loop runs for the [172:20] first time, in keyword takes one which [172:23] is the initial value, stores it in the i [172:26] variable, then we are printing it here. [172:28] Then on the second run we are [172:31] incrementing the value of i by 1. [172:33] Current value of i is 1. So 1 + 1 [172:36] becomes 2. So the in keyword takes that [172:40] value stores that in the i variable. [172:42] Then we are printing here. Now what [172:45] happens if [172:47] we don't specify the increment value? As [172:51] you can see we still have the same [172:53] output. This is because by default the [172:57] Python increments the value by one. One [173:01] is the default increment value. As you [173:05] can see it is working the same without [173:08] specifying it. Now we can specify a [173:12] specific number as well. For example [173:15] two. This time the the value of I will [173:19] be incremented by two. So let's execute [173:22] the code. we have a different output [173:25] right. So when this loop runs for the [173:27] first time value of I becomes one. So we [173:30] are printing one. On the second run the [173:33] value of I gets updated right? The [173:35] current value of I is 1. Now increment [173:38] value is two. Right? So 1 + 2 becomes [173:44] three. So the three gets stored in the [173:47] I. So we are printing that down here. [173:50] That's why we have three. On the third [173:52] run, the current value of I is three. [173:56] The increment value is 2. 3 + 2 becomes [173:59] five. So we are printing that here. [174:02] Right? So it keeps repeating as long as [174:05] the value of i remains less than the [174:08] value being specified here. Okay? So [174:10] guys, use the third value only if or [174:14] when you need to increment by a specific [174:17] number. If you want to increment it by [174:20] one, then you can leave it uh like this. [174:24] By default, it increments by one. And we [174:27] also do not need to specify the first [174:30] value or the initial value. Let's [174:34] execute the code. This time we have a [174:37] slightly different output. We have [174:39] numbers being printed from 0 to 11. Now [174:43] here if you do not specify starting [174:46] value and increment and you only specify [174:50] a number like 12 by default Python [174:53] starts with loop with zero. As you can [174:55] see the loop is starting from zero. So [174:57] when this loop runs for the first time [175:00] value of i is initialized [175:02] uh with zero by default then we are [175:05] printing that here by default it [175:07] increments the loop by one. So it keeps [175:10] repeating until the condition becomes [175:12] false. So guys, that's how the [175:15] So that's how the range function works. [175:18] And of course, if you want your loop to [175:21] start with a specific number, then yeah, [175:24] you have to explicitly specify that [175:26] number here separated by comma. This [175:29] time I'm telling range function that the [175:31] loop will start from one and run up to [175:34] the number specified here. this time [175:37] loop will start from one. So that's how [175:41] the range function works. In this video [175:45] we are going to create a table using a [175:49] for loop. This way uh it will increase [175:53] or strengthen your for loops [175:54] understanding. So let me quickly write [175:59] the code [176:02] 1 to 11 [176:09] print. [176:13] So I which is the for loops variable I [176:18] multiplied by two. So let's execute the [176:21] code and see what we get in the output. [176:24] As you can see we have the table of 2 2 [176:28] 4 6 uh up to 20 right. So what is [176:33] happening here? So when this loop runs [176:36] for the first time value of I is [176:38] initialized with one. So down here I am [176:42] doing uh this multiplication the current [176:44] value of I is uh 1. So 1 multiplied by [176:49] two is two. So we have two in the [176:51] output. Now when this loop runs for the [176:55] second time the value of I becomes two [176:59] because we are incrementing it by one [177:01] right now while current value of I is 2. [177:05] So here I'm multiplying the current [177:07] value of I which is 2 2 into 2 4 on the [177:11] third run value of I becomes 3. So I'm [177:14] multiplying 3 into 2 which is 6. We are [177:18] printing this table up to 20. So this [177:21] loop ends at 10. So when the value of i [177:24] becomes 10. So 10 into 2 20. That's the [177:28] last output. When the value of i becomes [177:31] 11, python is going to check if 11 is [177:34] less than 11. Condition is false. So [177:36] this loop terminates right here. So [177:38] guys, that's how you can you know [177:40] utilize the for loop to create tables. [177:43] Now let's uh actually you know format [177:45] this and uh um make our output more [177:49] presentable and logical. So I'm going to [177:52] use the f string. [177:55] So here within parenthesis sorry curly [177:58] braces [178:00] I into [178:04] 2 equal to now within the parenthesis [178:08] write the mathematical expression I into [178:12] 2 [178:14] and let's uh check the output now this [178:17] time we have a much better output okay [178:20] let's create space is on the both sides [178:24] of the [178:26] equal to sign [178:28] also create spaces here for a better [178:32] output or formatting. As you can see now [178:35] we have a much better output. So let's [178:37] break this down. When this loop runs for [178:40] the first time the value of i gets [178:43] initialized to one. The value of i is [178:46] one. Now here inside the f string I'm [178:50] printing the value of i. The current [178:54] value of i is one. So it prints this [178:58] part one. Then here it prints this uh [179:03] multiplic multiplication [179:05] sign as you can see. Now here two I'm [179:09] printing two as you can see two. It [179:11] prints it as it is right. then equal to [179:14] it is printing equal to then within the [179:16] parenthesis I have sorry curly braces I [179:19] have written this mathematical [179:20] expression so here I am multiplying I [179:23] current value of I is 1 I'm multiplying [179:26] it with two so current value of I [179:29] multiplied by two is equal to two on the [179:32] second run value of I becomes two so it [179:35] prints two it prints this part as it is [179:38] then it multiplies 2 into two so we have [179:42] four. So guys, that's how we have [179:44] formatted this output. I hope you have a [179:48] bit deeper understanding of the for [179:51] loop. So that's it for this short video. [179:54] In this video, we are going to learn [179:55] about the break statement. The break is [179:58] used to stop or exit out of a loop. [180:01] Typically, a loop keeps running or [180:03] executing its block as as long as the [180:06] condition is true. Right? However, there [180:09] are certain cases where we need to exit [180:12] out of a loop early when uh a specific [180:16] condition is met. Meaning, we don't have [180:18] to keep running the loop until the [180:21] condition becomes false or we want to [180:24] stop execution once a task is complete [180:27] to avoid unnecessary iterations. Using [180:30] the break statement, we can make our [180:32] script more efficient by allowing [180:34] controlled exits from loops. Now let's [180:37] dive into the practicals. I'm going to [180:40] create a simple loop that will print uh [180:44] let's say 10 numbers. So for i in [180:48] range the loop will start from 1 and run [180:53] up to the number 10. Now 10 + 1 write 10 [180:59] + 1 colon [181:02] print. Now print the loops variable [181:05] which is I. Let's execute the code and [181:09] we have the expected output. Right? Now [181:12] next thing that I want to do is exit the [181:17] loop when it reaches at a certain uh [181:20] number. For example, when this loop [181:22] reaches at uh number five, then I want [181:25] to exit or teri terminate this loop. I [181:29] don't want uh to print rest of the [181:31] numbers or I don't want to continue the [181:34] iteration after five. This is actually [181:37] simple. We just need to implement the [181:40] break statement. So if space now write [181:43] the loops variable which is I if I equal [181:48] to now specify the the number where you [181:52] want to stop the loop at. For me it is [181:55] going to be five six. In the if [181:59] statements block write break. Let me [182:04] execute the code. As you can see we have [182:07] the expected output. Right? We are [182:09] printing numbers only up to six. After [182:12] it uh we don't have anything being [182:16] printed because loop gets terminated [182:18] after six. Let's see how uh let's break [182:21] this uh down. This loop starts from one. [182:25] So when this loop runs for the first [182:27] time, the value of the for loops [182:30] variable which is i is initialized with [182:33] one. So the current value of i is one. [182:36] When this loop runs for the first time [182:38] down here, we are printing the current [182:40] value of i which is 1. So we have one in [182:44] the output. In the if statement, I'm [182:46] checking if the current value of i which [182:49] is 1 is equal to six. Obviously [182:51] condition is false right? 1 is not equal [182:54] to six. Since this condition is [182:56] evaluated to false, the block of if will [183:00] not be executed where we have the break [183:03] statement. Now control moves back to the [183:06] for loops uh structure. Now the value of [183:10] i gets incremented by one. Now value of [183:14] i becomes two. So here we are printing [183:16] the current value of i which is two. [183:19] Again here I'm checking if the current [183:21] value of I which is 2 is equal to six. [183:24] Condition is false. Therefore the block [183:27] of if will not be executed. Now Python [183:31] keeps repeating uh these steps until the [183:34] value of I becomes six. So when the [183:37] value of I becomes six down here we are [183:42] printing the value of I which is six. So [183:45] six gets printed. Now in the if [183:48] statement here I'm checking if the [183:50] current value of I which is 6 is equal [183:53] to six. Condition is obviously true. Six [183:56] indeed is equal to six. Now once this [183:59] condition is evaluated to true the block [184:03] of if gets executed where we have simply [184:06] written the break statement. Now as soon [184:09] as the break statement is executed, [184:12] Python exits out of the loop or it [184:15] terminates the loop. Control immediately [184:19] moves out of the for loops uh block. [184:22] Right? It will not print rest of the [184:25] numbers or it will not complete the [184:27] iteration or loop which starts from 1 to [184:31] 10. Okay? Loop immediately stops at six. [184:35] the control immediately moves out of the [184:38] for loop as as soon as the value of I [184:41] becomes six. Let me actually uh write a [184:44] print statement outside of this for [184:46] loops block. [184:49] Hello there. [184:51] As you can see after six we have the [184:53] hello there uh being printed. So that's [184:58] what happened when the value of I became [185:00] six condition was evaluated to true the [185:03] break statement was executed and when [185:07] break was executed it immediately exits [185:11] out of the loop loop was terminated [185:14] right there then the execution continued [185:17] after the for loops block. So it [185:20] executed this line which is uh written [185:22] outside of this for loops block. That's [185:25] why the break statement is useful. [185:28] Sometimes we don't have to, you know, [185:30] run the complete loop. When a certain [185:33] condition is met, we can exit out of the [185:35] loop. Now, without the break statement, [185:38] this loop will keep running from 1 to [185:42] 10. It will complete all its cycles as [185:45] long as uh the condition remains true. [185:49] Okay, let me write uh the print [185:51] statement uh within the if statements [185:54] block. [186:05] As you can see the loop stops at six. [186:08] Right? So when value of I became six, [186:11] the block of if was executed where we [186:14] are writing this print statement and [186:17] printing the value of I which is six. [186:20] After it we have the break statement. So [186:23] as soon as break was executed the loop [186:27] terminated right there and control [186:30] immediately moved out of the for loops [186:33] block and it executed the line that is [186:37] written outside of the for loops block [186:40] right hello there as you can see now [186:42] what happens if I uh change six to let's [186:45] say three [186:47] this time the loop exits at three right [186:51] in this video we will Take a look at the [186:54] continue statement. The continue [186:56] statement is used in loops to skip the [186:59] current iteration and move onto the next [187:02] one. Let me simplify this. When Python [187:04] executes the continue statement inside a [187:07] loop, it will skip the rest of the code [187:10] or remaining lines of code in that loop [187:13] block and move onto the next iteration. [187:16] Now, let's dive into the practicals. [187:20] I'm going to create a simple loop [187:23] that will print uh numbers from 1 to 10. [187:29] Now let's print the for loops variable [187:31] which is I. And this loop will print [187:34] numbers from 1 to 10. As you can see, as [187:36] expected, we have the output. Now, next [187:39] thing that I want to do is skip a [187:42] particular number. For example, I I [187:45] don't want to print the number six. I [187:48] want to print all these numbers except [187:51] for the number six. So if you want to [187:55] skip a particular number or iteration [187:58] then we use something called the [188:00] continue statement. Let's see how we can [188:03] do that. So if first we have to check [188:07] when the value of i becomes six. This is [188:10] the number that we want to skip. So if [188:12] value of i equal to 6 then simply write [188:15] the continue statement inside the block [188:20] of the if statement. Now we also need to [188:24] print the for loops variable which is i. [188:27] Make sure that the print function is [188:29] written outside of the if statements [188:32] block and inside the for loops block [188:35] like this. Right? Let's execute the [188:38] code. As you can notice guys, we have [188:41] the expected output. So after five, we [188:44] have directly seven. Six is missing. So [188:47] let's see how it happened. So this loop [188:51] starts from one. So when this loop runs [188:53] for the first time, the value of i is [188:57] initialized with one. And here I'm [189:00] checking if the current value of i which [189:02] is 1 is equal to six. Condition is [189:05] obviously false. Since this condition is [189:07] evaluated to false, the block of if will [189:11] not be executed where we have written [189:14] the continue statement. So this block [189:17] will not be executed. Now here at line [189:20] number five, we are printing the value [189:22] of I which is uh one. The current value [189:26] of I is one. So one is being printed. [189:29] Now control moves back to the the for [189:32] loop. The value of I gets incremented by [189:35] one. Now it becomes two. Again, Python [189:38] checks if the current value of I which [189:40] is 2 is equal to 6. Condition is false. [189:43] Therefore, the block of if will not be [189:46] executed. And down here we are printing [189:50] the value of I which is two. So it gets [189:53] printed. Now Python keeps repeating [189:57] uh this process until the value of I [190:00] becomes six. So when the value of I [190:02] becomes six here Python checks if the [190:05] current value of I which is 6 is equal [190:08] to 6. Condition is obviously true right [190:11] six indeed is equal to six. So when this [190:16] condition is evaluated to true the block [190:19] of if gets executed where we have uh [190:22] written the continue statement. Now as [190:25] soon as the continue statement gets [190:27] executed, it will skip the current [190:30] iteration of the loop. Now skipping the [190:33] current iteration of loop means it will [190:36] not execute any code that is written [190:39] after the continue statement inside a [190:43] loop. Right? So after the continue [190:45] statement we have uh the print uh [190:48] function that is printing value of I. [190:51] Now current value of I is six. That's [190:54] why the six is missing because when the [190:57] value of I became six the continue was [191:01] executed and when continue got executed [191:04] it skipped all the code that is written [191:07] after it within this for loop after it [191:10] obviously is print statement that prints [191:13] the value of I. So I was not executed. [191:16] So that's how the continue statement [191:18] works. It doesn't exit the loop like the [191:21] break statement does. it just skips the [191:24] current iteration or cycle. So any code [191:27] that you write after the continue [191:30] statement inside a loop that code will [191:33] not be executed. It will ignore that [191:36] code and control immediately moves back [191:39] to the for loops structure. Now the [191:42] value of uh I gets incremented by one. [191:45] It becomes 7. So here I'm checking if [191:48] the current value of I which is 7 is [191:51] equal to 6. Condition is obviously [191:53] false. This time the block of if will [191:57] not be executed. The execution remains [192:00] normal. Now it will execute the print [192:03] statement where we are printing variable [192:05] I whose current value is seven. So it [192:08] gets printed. Let's say three. This time [192:12] it is going to skip three. Right? [192:14] Because when the value of i becomes [192:16] three, the continue gets executed and it [192:19] will not execute any lines of code that [192:22] that you have written after it within [192:25] within uh within a loop. In this video, [192:27] we will take a look at the while loop. [192:30] While is another type of loop available [192:32] in Python as well as in most programming [192:35] languages. The y loop is similar to the [192:38] for loop but it works a bit differently. [192:41] Just like a for loop, a Y loop typically [192:44] involves three part initialization, [192:46] condition check and increment. However, [192:49] the main difference between the two is [192:52] in how these parts are structured. In a [192:55] for loop, all three parts, [192:57] initialization, condition check, and [192:58] increment are usually written together [193:01] in a single line or structure within the [193:04] range function. Right? In a while loop, [193:07] they are separated. Initialization is [193:09] done before the loop starts. The [193:12] condition check is written in the while [193:15] statement itself. So increment can be [193:18] placed anywhere inside the loop block [193:21] depending where you want it to execute. [193:24] Now let's dive into the practicals and [193:27] write our while loop. First we need to [193:30] initialize the Y loop. So I =0. The Y [193:33] loop will start from zero. Now write the [193:36] while keyword. Here we need to tell the [193:40] Python how long this while loop will [193:43] run. Space I less than 10. [193:48] So this loop will start from zero and [193:51] will keep running as long as the value [193:53] of I remains less than 10. So in the [193:56] while we have to specify the condition [193:59] how long your loop will run. Now write [194:03] colon. After the colon the block of [194:05] while loop starts just like the for [194:08] loop. A while loop also has its own [194:10] sound block which is defined by the [194:13] indentation. Press enter. As you can see [194:15] it has automatically inserted four [194:18] spaces. For some reasons if it doesn't [194:21] add indentation or four spaces then [194:24] write the four spaces manually. 1 2 3 [194:27] four. Four spaces are the default [194:29] indentation. Now I'm going to print the [194:31] value of I. Now last part is increment. [194:36] Increment is always specified at the [194:39] end. So I'm going to increment the value [194:41] of I by 1 + 1. Okay, let's execute the [194:46] code and uh see what we get. Okay, we [194:49] have the output from 0 to 9. So let me [194:52] break this down. So here this is called [194:54] the initialization. [194:57] First we need to initialize the the y [195:00] loop. So I this is the y loops variable [195:02] and of course you can give any name to [195:04] your variable. So this loop starts from [195:07] zero. Now here I'm uh specifying the [195:09] condition. So i less than 10. So this [195:12] loop will keep running as long as the [195:15] value of i remains less than 10. The [195:17] current value of i is 10. Sorry, current [195:20] value of i is zero. So, Python checks if [195:24] the value of I is less than 10. So, 0 is [195:27] less than 10. So, condition is true. So, [195:30] when the condition is evaluated to true, [195:32] the block of while gets executed. Here [195:36] we have written print uh statement. So, [195:39] it prints the value of I which is zero. [195:43] So, it prints zero. Now, at line number [195:45] four, this is called the increment where [195:48] we increment our for loop. So I = I + 1. [195:52] Current value of I is 0. So 0 + 1 [195:56] becomes 1. Now 1 is stored in the [196:00] variable I. So value of I is updated. [196:04] Now control again goes to the Y loop. [196:06] Here it checks the current value of I [196:09] which is 1. 1 is less than 10. Condition [196:13] is true. So it prints one. Now value of [196:16] I is incremented by one again. Now [196:19] current value of I is 1. 1 + 1 becomes [196:22] 2. So again it checks if 2 is less than [196:26] 10. Condition is true. It prints true. [196:28] So it keeps repeating this block as long [196:31] as the condition remains true. Now when [196:34] the value of i becomes 10. So here [196:37] Python checks if the current value of i [196:39] which is 10 is less than 10. Condition [196:42] is false. 10 is not less than 10. It is [196:44] equal to 10. So condition is evaluated [196:47] to false. So when the condition is [196:49] evaluated to false the while loop [196:52] terminates here okay it will not ex [196:55] execute the code that you have written [196:57] in the block of while. So that's how the [197:01] while loop works. First we need to [197:03] initialize it. Then we need to specify [197:06] the condition how long you want to run [197:09] this while loop. Then at the end we have [197:12] to increment or update the while loop. [197:15] increment part is always specified at [197:18] the end. [197:21] So let's uh execute hello world. [197:25] Now this loop runs 10 times. So it [197:30] executes the hello world 10 times. [197:38] As you can see this loops sorry. Yeah [197:39] this loop runs 10 times from 0 to 9. Now [197:44] you can also write uh less than equal to [197:47] 10. This time it will print numbers from [197:50] 0 to 10. As you can see because here we [197:53] are using less than equal to. So when [197:56] the value of i becomes 10, python checks [197:58] if the current value of i is 10 or [198:01] current value of i which is 10 is less [198:04] than equal to 10. Right? First it checks [198:06] is it less than 10. Condition is false. [198:10] Then we also have specified equal to. So [198:12] it also checks if the 10 is equal to 10 [198:16] condition is true. Since condition is [198:18] true, so block of while gets executed. [198:21] So it prints 10. But when value of i [198:24] becomes 11, the condition gets evaluated [198:26] to false. 11 is not less than equal to [198:30] 10. So the y loop terminates here. So [198:33] guys, this is the main takeaway for the [198:36] y loop. First we need to initialize it. [198:39] Then we need to specify a condition how [198:43] long you want the while loop to run. And [198:46] the increment part is always specified [198:49] at the end. However, the increment part [198:53] it doesn't always have to be at the end. [198:55] Typically, it is written at the end, but [198:58] you can place it uh anywhere you want [199:01] inside the block of y loop like this. It [199:05] also works like this. But it will change [199:08] the uh output slightly. As you can see, [199:11] for the most part, it is uh written at [199:14] the end. But in certain cases, you might [199:17] need to write it at the beginning or [199:20] middle. This time, as you can see, it [199:22] has changed the output slightly, right? [199:26] Even though the loop starts with zero, [199:28] but it is not printing zero, right? It [199:31] is printing from 1 to 11. Why? So when [199:34] this loop runs for the first time here [199:37] the current value of I is zero. So [199:40] Python checks if 0 is less than 10 [199:42] condition is true. Now here at line [199:45] number three we are incrementing or [199:48] updating value of I. So I whose value is [199:51] 0. 0 + 1 becomes 1. Now current value of [199:54] I is updated to one. So here we are [199:57] printing one. Right? As you can see. So [200:00] zero never gets printed. Now here we [200:04] have an unusual thing right? Even though [200:08] this loop runs only up to number 10 but [200:11] it is printing 11 as well. Why? So when [200:15] the value of I becomes 10 condition is [200:18] true right? I is less than equal to 10. [200:21] Now add line number three. I we are [200:24] incrementing the value of I by 1. So [200:27] current value of I is 10. 10 + 1 becomes [200:30] 11. So we are printing 11 here. Right? [200:34] Now control goes back to the for loop. [200:36] Now value of i is 11. 11 is not less [200:40] than equal to 10. So condition is [200:42] evaluated to false. So the loop [200:44] terminates right here. So guys, that's [200:46] how the loop works. In this section, we [200:50] will explore functions. They are a [200:52] fundamental concept in programming [200:55] because they offer two major benefits or [200:58] features. modular code and code [201:01] reusability. Let's start with modular [201:04] code. Modular code means breaking down a [201:07] large program into smaller independent [201:11] units or sections called functions. This [201:14] makes the software easier to develop, [201:17] maintain and update. Until now, we have [201:20] been writing code line by line which [201:23] works fine for small programs or [201:26] applications. But when your code grows [201:30] into hundreds or even thousands of [201:32] lines, it becomes harder to manage. [201:36] Without modularity, large programs can [201:39] become messy and difficult to maintain. [201:42] That's exactly what functions help with. [201:46] Functions allow us to break a large [201:48] program into smaller manageable sections [201:51] by dividing it into multiple functions [201:55] where each function is responsible for a [201:58] specific task. For example, let's say [202:00] you are building a calculator that can [202:03] perform multiple operations such as [202:06] addition, subtraction, multiplication, [202:08] and division. Without functions, all the [202:11] code would be written sequentially in a [202:14] single block which makes it hard to [202:17] read, maintain and update. Now with [202:20] functions, each function can be written [202:23] in its own block or section. We can [202:26] create one function for addition, one [202:29] for subtraction, one for multiplication [202:31] and so on. This approach makes your code [202:35] cleaner, more organized, and easier to [202:38] debug and expand later. Most [202:40] importantly, once you create a function, [202:43] it can be reused throughout your [202:46] program. This is known as code [202:49] reusability, which simply means you can [202:52] use the same function multiple times, [202:54] avoiding the need to write duplicate [202:58] code. Now, let's dive into the [203:00] practicals. So write def. The def [203:04] keyword is used to create or define [203:08] functions. [203:09] Space. Now give a name to your function. [203:12] I'm going to create a simple function to [203:14] add numbers. So I'm going to give my [203:16] function name add. And of course you can [203:19] give any name to your function. Now [203:22] write parenthesis. Parenthesis are [203:24] important. That's how Python recognizes [203:27] a function. Now write colon. Colon is [203:30] important. Colon basically tells Python [203:32] that after it the body of this function [203:36] starts just like other control [203:39] structures like loops, if statements [203:41] have their own bodies, a function also [203:44] has its own body. The code that you [203:47] write inside the body or block of a [203:50] function. That code gets executed when [203:53] you call or use a function. And how do [203:57] you define body of a function? Well, it [204:01] uses indentation to define body or block [204:05] of a function. Press enter. As you can [204:08] see, it has automatically inserted four [204:11] spaces. This is the indentation, right? [204:14] And for some reasons, if your code [204:16] editor is not inserting four spaces, [204:20] then you can add or insert them [204:23] manually. 1 2 3 four. Four spaces are [204:26] the default indentation in Python. Now [204:30] let me write a print statement. [204:33] Sum is add two numbers. [204:38] Okay, let's execute the code and we [204:41] should have 79 in the output. However, [204:44] here we don't have any output at all [204:47] even though we have created this [204:49] function. Right? Well, here we have done [204:53] the first part. We have created or [204:56] defined this function. Now to use a [204:58] function, we have to call it. How do you [205:02] call a function? Outside of the block of [205:05] this function, write the exact function [205:07] name that you want to call. For me, it [205:10] is add. So here down here, write add. [205:13] Then parenthesis. Parenthesis are [205:15] important. So when you call a function, [205:18] then Python is going to execute the code [205:21] that you have written here. [205:25] This time we should get the output here [205:28] sum is 79. So we have the expected [205:30] output. So this part at line number five [205:33] this is called calling a function. [205:36] Calling simply means using a function [205:38] that you have defined and this is called [205:41] the function definition. In the function [205:43] definition part we define functionality [205:46] for a function. What your function [205:49] actually does. In in my case, my [205:51] function is simply adding these two [205:54] numbers. That's how the functions work. [205:57] Now, one thing that you must remember is [205:59] that function must always be called [206:03] below its definition. You can't call a [206:06] function like this above the definition [206:09] like this. [206:13] As you can see, add is not defined. So [206:17] function must a function must always be [206:20] called below its definition outside of [206:23] its block of course like this. [206:27] Now the best thing about functions is [206:31] that once you create a function then we [206:34] can reuse that function as many times as [206:36] you like. Okay, let's uh [206:40] uh add a few more print statements [206:43] inside the block of this add function [206:46] inside the [206:49] body of uh add function. [206:53] Now these two lines as you can see they [206:54] are using the same level of indentation. [206:57] So these two lines exclusively belong to [207:00] this add function. So when you call this [207:03] add function these two lines will be [207:05] executed because they belong to this add [207:08] function as you can see right print [207:14] is is [207:18] now we have these three lines that are [207:21] part of uh this function they will be [207:24] executed when I call it as you can see. [207:28] Now the best thing about functions is [207:30] that uh they are reusable. What it [207:34] basically means once you create a [207:35] function you can reuse it as many times [207:38] as you like. [207:40] So let's reuse this function add. [207:45] As you can see we have uh reused this [207:49] add function successfully. Right? So at [207:51] line number six when I called the [207:53] function Python executed this uh add [207:56] function. Right? And uh it printed all [208:00] the lines written inside its body. And [208:02] line at line number eight, I called this [208:05] function again. Then it uh executed this [208:09] function and executed all the lines uh [208:13] written inside its block. This way you [208:15] can reuse a function as many times as [208:19] you like. You just need to call it like [208:22] this. [208:24] Okay. Now we have uh called this [208:27] function four times. So it will be [208:30] executed four times. This is a very [208:32] convenient way to avoid writing [208:35] repetitive code. Right? Without [208:37] functions we would have to write the the [208:40] same code again if it is needed in our [208:43] program. Right? With functions we can [208:45] just create a function once then use it [208:48] as many times as we like. Now let's [208:51] create a few more functions for better [208:54] clarity. [208:55] Now I'm going to create a function to [208:58] multiply [209:00] numbers. [209:02] Rent [209:08] is [209:11] define [209:13] division. [209:21] Let's uh execute the code. As you can [209:24] see, we have sum even though we have uh [209:27] created or defined two more functions [209:30] division and multiplic multiplication [209:33] but we have no output for these two [209:35] functions because we have defined these [209:38] functions but we have not called them [209:41] yet. So let's uh call the multiplication [209:46] function. As you can see multiplication [209:48] function write the function name as it [209:51] is. Now we have multiplication here. [209:54] Let's call the division function. [210:00] As you can see division is this. So we [210:04] have defined these three functions. Then [210:07] we we are calling them. Right [210:10] now functions are executed in the same [210:13] order as you call them. For example here [210:16] I I have first called the add function. [210:19] Python is going to execute this add [210:21] function first. Then I have called the [210:24] mult multiplication function. It will [210:27] execute uh the multiplication and at the [210:29] end we have this division function. It [210:31] will be executed at the end. Let's put [210:34] it at the top. [210:36] Now we have changed the order of [210:39] execution. This time the division [210:41] function will be called first then add [210:44] and multiplication as you can see. So [210:48] guys that's how you can create and call [210:51] functions. Now what uh you are going to [210:54] do is u create two more functions. As [210:58] you can see I have created functions for [211:01] add, multiplication, division but I have [211:03] not created functions for subtraction [211:07] and modulus. So what you are going to do [211:09] is create functions for modulus and [211:13] subtraction. Just define them then call [211:16] them. It should be easy. So that's it [211:19] for this video guys and of course if you [211:21] come up with any problems you can let me [211:24] know in the Q&A section. In this video [211:26] we will discuss arguments and the [211:29] difference between arguments and [211:31] parameters. Arguments are essential [211:33] components of functions in programming. [211:36] Without arguments, functions would not [211:39] be as flexible or powerful. Arguments [211:42] allow us to pass data into a function. [211:46] The values or data passed into the [211:49] function are called arguments. Once you [211:51] pass arguments to a function, then the [211:54] function can use uh those values to [211:58] perform tasks. Let's say you want a [212:00] function to add two numbers. For the [212:02] function to perform that calculation, it [212:06] first needs the two actual numbers. This [212:09] is where arguments come in. By using [212:12] arguments, we can pass the required [212:14] values into the function. The function [212:17] then takes those values, processes them, [212:19] and returns a result. Parameters are the [212:23] variables that receive values in the [212:26] function definition. Now, let's dive [212:29] into the practicals. Let me quickly [212:32] create a function add. Let's add [212:38] two numbers. and let's call the [212:41] function. Let's execute the program. [212:44] Okay, we have the expected output, [212:46] right? That's how we have been working [212:48] with functions so far. We define a [212:52] function, then call it. Now, we are [212:54] going to make it interesting. We are [212:57] going to pass arguments to a function. [213:00] Now, how do you pass arguments to a [213:02] function? Well, inside the parenthesis, [213:05] write u uh any two numbers. Let's say 12 [213:09] and 89. Now these are basically called [213:13] the arguments. Arguments are nothing but [213:17] the data that you pass to a function. So [213:20] I'm telling this add function take these [213:23] two numbers or arguments then give me [213:27] their sum. Now once you pass data or [213:30] arguments to a function those arguments [213:34] must be received where we have defined [213:38] the function. Now this add function is [213:40] being defined here at line number one. [213:42] Right? Now inside the parenthesis of [213:45] this add function we must receive these [213:48] two arguments. Once we receive arguments [213:51] then we will be able to use these values [213:55] inside uh the definition of this [213:58] function. How do you receive arguments? [214:00] Well, simply write the variable names a [214:04] comm, b. Now these variables are [214:07] specifically called parameters. [214:10] Parameters are the variables that you [214:12] define or list inside the parenthesis of [214:16] a function definition. First argument [214:20] gets stored in the first parameter or [214:22] variable. Second argument gets stored in [214:25] the second variable. Now let's print [214:29] value of these variables. A okay let's [214:32] use string formatting. A equal to A, B= [214:41] B. [214:44] As you can see guys, a equal to 12 and b [214:47] equal to 89. So I passed 12. It was [214:50] received by the parameter or variable a. [214:54] As you can see a equal to 12 and second [214:58] argument was stored in the second [215:02] parameter b then we are printing its [215:06] value. So we are receiving the the [215:08] arguments successfully. Now once we [215:10] receive the arguments then we we can use [215:13] them however we like. So what I'm going [215:15] to do is uh add these two numbers. Sum [215:18] is [215:20] a + b. [215:23] Okay. Sum is a + b. So we have the [215:25] expected output. Right? We are adding a [215:28] + b. These two variables are storing the [215:31] data that has been passed as an argument [215:34] here. Right? First value gets stored in [215:36] the first variable. Second value gets [215:39] stored in the second variable or [215:41] parameter a b. Now we are using these [215:44] two variables inside the function. Now [215:48] let's uh pass third argument [215:51] 67. Now the arguments must be separated [215:54] separated by a comma like this. This [215:57] time we have passed these three [215:59] arguments. Now when we pass three [216:02] arguments then all the three arguments [216:04] must be received inside the function [216:08] definition like this a b c. If you don't [216:11] then it will throw an error as you can [216:14] see add takes two positional arguments [216:17] but three were given. So let's receive [216:21] this as well. C. Now C is holding the [216:25] third argument [216:27] and now we have the expected result. Now [216:31] the best thing about arguments is that [216:34] we can pass different arguments to the [216:36] same function. So let's call the add [216:39] function again. This time I'm going to [216:41] pass different [216:44] arguments or values like this. [216:49] As you can see, we have called this add [216:53] function twice, but we have passed [216:55] different values to the same add [216:57] function. That's the beauty of functions [217:01] combined with uh combined with [217:04] arguments. [217:06] We can also pass other type of data. It [217:09] doesn't have to be numbers. We can pass [217:12] uh strings, decimal numbers as well. So, [217:15] let's create another function that print [217:17] names. print names. Print name. I'm [217:21] going to pass [217:23] Sunny, [217:26] Dimalu. [217:28] Let's define the print name function. [217:32] Print name. [217:35] Now, as you can see here, uh I'm calling [217:38] this print name function and and passing [217:41] these two string values as as arguments. [217:45] Now these arguments must be received [217:49] inside the parenthesis of this print [217:51] name function. So a b okay let's uh give [217:58] some meaningful variable names f name [218:02] last name [218:04] print [218:08] first [218:10] name is [218:13] f name last name is last name l name. [218:23] Let's execute the code. As you can see, [218:25] first name is Sunonny, last name is [218:27] Timalu. Right? So, we have created two [218:30] functions add and we are passing the [218:34] numbers to it and I have also created [218:37] print name function and I'm passing [218:40] string values to it or string arguments [218:43] to it. then receiving them here and [218:46] utilizing the arguments being passed to [218:49] the print name function. Now we can also [218:52] use variables as arguments right for [218:55] example [218:57] a equal to b equal to this [219:02] c equal to this. Now instead of directly [219:05] passing values I can pass these [219:09] variables as an arguments right. Yeah, [219:12] this is pretty much the same here. [219:14] Instead of passing values directly, I'm [219:17] passing these three variables. And of [219:20] course, these two three variables are [219:22] storing the numbers, right? A= 12, B= 6, [219:26] 7, and C= 9 0. So I'm sending them as [219:30] arguments. Variable A which is storing [219:34] 12, it gets stored in the A variable. [219:38] Second value gets stored in the B. Third [219:42] value C which is holding 90, it gets [219:45] stored in C. So let's execute the code [219:48] and we have the expected result. Before [219:53] we dive deeper into functions, it is [219:55] important to understand variable scope [219:58] because it plays an important role in [220:00] writing clean and error-free code. [220:03] Variable scope defines where a variable [220:06] can be accessed or modified within a [220:09] program. It is determined by where the [220:13] variable is created. In Python, there [220:16] are two primary types of variable scope. [220:19] Global scope and the local scope. A [220:22] global variable can be accessed from any [220:25] part of the program including inside [220:27] functions and outside of function. [220:30] Global variables are created in the main [220:33] body of the script or program and [220:36] outside of any function definition. Now [220:39] a local variable is a variable that can [220:41] only be accessed within the function [220:44] where it is declared or created. It [220:47] can't be accessed outside the functions [220:50] block where it is defined. Now let's [220:53] dive into the practicals. We are going [220:56] to start with uh the global variables. [220:59] Let's create a equal to 56. [221:03] And I'm going to also create a a [221:06] function [221:09] print. Let's access this a variable [221:12] inside this add function. [221:15] Inside the add [221:18] function a equal to [221:21] a. Let's call the add function and let's [221:27] access the same variable a outside of uh [221:31] the function as well. Outside [221:35] of the function a equal to [221:42] let's execute the program. Okay, it is [221:45] working as it should. So what basically [221:48] is happening here? This a equal to 56. [221:50] This is a global variable. A global [221:54] variable is is a variable that is [221:56] created outside of a function. Right? [222:00] This a as you can see it is created [222:02] outside of a function. So when you [222:05] create a variable outside of a function [222:08] that variable by default becomes the [222:11] global variable. A global variable can [222:13] be accessed by anyone and anywhere in [222:18] your program. So here we have accessed [222:21] this a variable inside this add function [222:23] as well as outside of a function as [222:26] well. Right? So that's the global [222:28] variable. All the global variables that [222:31] you create outside of a function by [222:33] default they are the global variables [222:35] and remains accessible to everyone [222:38] inside a program. So this is as simple [222:41] as that. Now let's move on to the global [222:44] variables. Sorry, a local variables. A [222:48] local variable is always created inside [222:52] a function. So inside the add function, [222:54] let me create x= 89. [222:58] Let's access x print [223:03] x = [223:05] x. Right? [223:08] Okay. Here I'm able to access the x as [223:11] you can see x equal to 89. Like I was [223:15] saying a local variable is created [223:18] inside a function. You don't need to [223:21] perform any additional steps to create a [223:25] local variable. So when you create a [223:27] variable inside a function that variable [223:29] automatically becomes a local variable. [223:32] A local variable is only accessible [223:35] within the function where it is created. [223:38] Right? This X as you can see it is [223:40] created inside the add function. Now it [223:43] can only be accessed within this add [223:46] function. If I attempt to access it [223:49] outside of add function or in other [223:53] functions then we won't be able to [223:56] access it. So let's print x equal to [224:05] x and we have an error as you can see x [224:09] is not defined right even though the [224:13] variable x as you can see it is being [224:16] created here but it is not accessible [224:18] outside of this function a local [224:21] variable can only be accessed by the [224:25] function where it is created right the [224:28] this is a as you can see this is a [224:30] global variable I'm able to access it [224:33] inside the add function as well as [224:35] outside of uh the add function as well [224:38] whereas this local variable x I'm able [224:41] to access it here inside the add [224:44] function but I can't access it outside [224:46] of the add function now so scope of a [224:50] local variable remains within the [224:53] function where it is created [224:58] So let's see how we can make a local [225:00] variable uh global. We have the global [225:03] keyword to make a global variable uh [225:05] sorry local variable global. First we [225:08] need to uh define the variable global x [225:13] equal to 78. Let's execute the script [225:16] and we should have an error. As you can [225:19] see at line number four four we have an [225:22] error global x= to 78. [225:26] Now if you want to make a local variable [225:29] global first we have to declare that [225:32] variable. You can't assign the value in [225:35] the same line like this. First declare [225:37] it like this global x then assign a [225:42] assign a value to it in a new line like [225:45] this. [225:48] Now it is working just fine. As you can [225:50] see I am able to access X here inside [225:54] the add function as well as I am able to [225:57] access the same X variable outside of [226:00] the function as well. So if you want to [226:04] make a local variable global then we [226:06] need to use the global keyword. Let me [226:09] remove the global keyword. [226:12] Now we have an error. As you can see [226:16] X is not defined at line number 11. [226:20] This X is accessible to to the add [226:23] function at line number six. Right? But [226:25] after removing the global keyword, the [226:28] same X variable is not accessible [226:30] outside of this function. So let me [226:34] write the global keyword again. Global [226:37] X. Now we have made this X a global [226:41] variable. Now it will be accessible [226:44] outside of this function as well as you [226:47] can see. So that's the difference [226:49] between global and local variables. Now [226:52] understanding variable scope like global [226:55] and local is extremely important. [226:57] Without proper scope control programs [227:00] become difficult to manage and debug. [227:03] You should not make a local variable [227:06] global unless you have a very specific [227:09] reason to do so because once a variable [227:12] is global, it becomes accessible [227:14] everywhere in the program. This means [227:16] that it can be modified or overritten by [227:20] different functions or even from outside [227:23] any function which can easily lead to [227:26] unexpected behaviors and bugs. So again, [227:30] don't make a local variable global [227:33] unless you have a very specific reason [227:35] to do so. Let me remove the global [227:39] keyword. [227:40] Now if let's say [227:44] if I create another function and uh [227:49] create the same variable x x equal to [227:51] this. Now I have the same x variable in [227:55] the two different functions. Well, these [227:58] two are totally different variables. [228:00] They are independent variables. This x [228:04] is a separate variable that belongs to [228:06] add function. This x is a separate [228:09] variable that belongs to to multip this [228:12] multiplication function. In this video, [228:14] we will discuss the return statement in [228:17] Python, which is a fundamental concept [228:20] when working with functions. The return [228:23] keyword allows a function to send a [228:25] value back to the part of the program [228:28] that called it. In simple terms, the [228:30] return statement sends the result or [228:33] value back to the place where the [228:35] function was called. This allows the [228:38] result to be stored in a variable. You [228:41] can also print the result or use the [228:43] data or result in further processing. [228:46] Now let's dive into the practicals. I'm [228:49] going to create a simple function that [228:52] returns sum of two numbers. So add let's [228:56] return [229:00] sum of 34 + 44. Let's call the function [229:05] and execute the code. Okay, we don't [229:09] have any output. This is because we have [229:11] not printed uh any value yet. Right now [229:16] here I'm using this return keyword or [229:19] statement. Now the return basically [229:22] returns a value to the part where a [229:26] function has been called. It returns sum [229:30] of these two numbers to the part where [229:33] you have called this add function. Okay. [229:36] So when return gets executed, it sends [229:40] the sum of these two numbers to the add [229:43] function wherever you call it. Now once [229:46] a value is sent or returned to a [229:50] function then we can utilize that value. [229:52] We can simply print [229:55] that value like this. Okay, as you can [230:00] see 78, right? So return sent the result [230:04] of these two numbers to the part where [230:07] this function has been called. It is [230:10] being called here at line number four. [230:12] Once a value is returned to a function [230:15] then we can print that value like this [230:19] add function. Now the recommended and [230:22] standard way of dealing with uh a [230:26] returned value is to store that value in [230:29] a variable because once you store a [230:31] value in a variable then that value can [230:34] be reused later in the program. So a [230:37] equal to add. So let's print [230:42] a. [230:44] So we have the same result 78. So what [230:46] basically is happening here? The return [230:49] statement returned sum of these two [230:52] numbers to the function where it is [230:55] being called. It is being called at line [230:57] number four. When the value was returned [231:00] to it, we are storing that returned [231:03] value in the variable A. Then we are [231:06] printing that variable A. Right? So we [231:09] have the 78 as an output like this. [231:12] Let's modify it a little. [231:16] So that's the basic working of the [231:18] return statement. Uh what we are going [231:22] to do is uh [231:26] create variables A B [231:30] C = A + B. Now I'm returning C. [231:37] As you can see we have 112. So this time [231:40] I have created variables A B and then [231:43] adding these two variables and storing [231:45] that result in the variable C. Then I'm [231:48] returning the variable C which is [231:52] storing the sum of these two numbers. [231:54] Right? Now when the Python executes the [231:58] return statement, it does not execute [232:02] anything that is written after the [232:05] return statement. For example, if I [232:09] write the print statement [232:12] after return, Python will not execute [232:16] this line at all. As you can see, it has [232:19] not been executed. So, as soon as the [232:21] return gets executed, the execution [232:25] stops right there. Okay, it returns [232:28] value to the part where the function has [232:30] been called and it will ignore all the [232:33] lines of code that you write after it. [232:36] Those lines will not be executed. Now, [232:39] one thing that I want to clarify that [232:41] the return does not stop execution of [232:44] the entire program. It only stops the [232:47] execution of the function where you use [232:50] the return keyword. Right here after [232:53] executing the return statement, Python [232:57] will stop executing any lines that you [232:59] write after it. Now you can also return [233:03] string values [233:06] like this. Let's say sunny. [233:10] Now this time it is returning the sunny [233:13] to the add function. Then I'm storing [233:16] that in the a and printing it. Right? [233:19] Let's use arguments. [233:22] So what I'm going to do is uh I'm going [233:24] to pass these two arguments to the add [233:27] function. Let's receive them. [233:31] And uh [233:36] let's return [233:38] a + b. [233:43] store that result in a sum [233:47] print [233:49] sum [233:51] and we have the output here. So what is [233:53] happening here? I'm passing these two [233:55] values as an argument to the add [233:58] function and receiving them here. And [234:01] then I'm adding these two values. And [234:05] then return statement is going to return [234:08] the sum of these two numbers to the add [234:11] function where it has been called. It [234:13] has been called here. Now the value that [234:18] is has been returned gets stored in the [234:22] sum variable. And down here I'm printing [234:24] the sum. So that's how guys the return [234:27] statement works. It will get clearer as [234:29] we progress in the course. In this [234:32] video, we will create a mini project. We [234:34] will build a calculator. The goal of [234:37] this project is simple. We want to apply [234:40] everything we have learned so far and [234:42] use it to build something useful. We [234:46] will apply concepts such as type [234:48] casting, functions, conditional [234:49] statements, and more. The program will [234:52] ask the user to enter two numbers. Then [234:55] the user will choose the operation they [234:57] want to perform such as addition, [235:00] subtraction, and others. Based on the [235:02] user's choice, the program will perform [235:05] the selected operation and display the [235:08] result. Now let's dive into the [235:10] practicals. First thing that we are [235:13] going to do is allow users to enter two [235:16] numbers. Then we will perform [235:19] calculations based on their choice. So [235:23] num one variable is going to store the [235:27] first number that user enters. [235:32] Let's copy and paste it. [235:35] The num two variable is going to store [235:39] the second number that user enters. And [235:42] of course we need to perform type [235:45] casting. We need to convert user inputs [235:48] into a number. As we already know, by [235:51] default the input function treats all [235:54] inputs as string. So to perform [235:57] calculations, we must convert strings [236:00] into numbers. We can use float or [236:04] integers. I'm going to go with integer. [236:07] So int parenthesis. Now close the ints [236:11] parenthesis at the end like this. Repeat [236:14] the same thing for uh second input. [236:18] Let's execute the code. Okay, it is [236:21] working just fine. Now, next step is to [236:25] display a menu to user. Right, we are [236:28] going to display a menu that will give [236:31] the users the option that they can [236:34] select from or menu item that they can [236:36] select from print. So one is for uh [236:43] addition. [236:45] Let me copy paste. [236:49] Two is for uh multiplication. [237:01] Four is for subtraction. [237:06] Let's execute the code. Enter first [237:08] number, second number. As you can see, [237:11] after user enters these two numbers, [237:14] then we are displaying this menu to the [237:17] user. Right? User can select these [237:20] operations. For example, if user wants [237:22] to perform addition of these two [237:25] numbers, then they can select one. If [237:28] they want to multiply, then they can [237:31] select two, three and so on. Now next [237:35] thing that we need to do is store the [237:39] user's choice. Right now my program is [237:43] not allowing user to enter their choice [237:46] right to what operation they want to [237:48] perform. So let's create a variable [237:50] called choice equal to input. So enter [237:56] enter your choice. [238:00] Let's execute the code. [238:03] As you can see now we have the options. [238:05] This is the menu that a user can select [238:08] from I want to perform addition. So I'm [238:11] going to enter one. As you can see I'm [238:14] able to enter one. So whatever value the [238:17] user enters that value gets stored in [238:20] the choice variable. Now using this [238:22] choice variable we can perform the [238:25] calculation based on user's choice. [238:28] Before we proceed further, make sure to [238:31] have space after choice like this. This [238:35] way it looks better [238:37] and uh user experience will be a much [238:40] better [238:42] as you can see. Enter choice. Now we [238:44] have a much better formatted output. Now [238:47] let's write functions for each of these [238:50] functionalities. First we need to check [238:53] the user's choice. So whatever user [238:55] enters that value gets stored in the [238:58] choice variable. So choice if user's [239:03] choice is one then we are going to [239:06] perform addition. So what I'm going to [239:08] do is uh call the add function pass [239:12] num one and num two as arguments. Now [239:18] the num one as you can see num one [239:20] stores the first number that user [239:22] enters. num to stores the second number [239:24] that the user enters. We are passing [239:27] these two numbers as arguments to the [239:29] add function. [239:31] Now we need to define the add function. [239:34] Define [239:36] add. Now receive the arguments. The [239:39] first arguments num one gets stored in [239:43] A. Second arguments get gets stored in [239:46] B. Now let's uh add the numbers. [239:52] Addition [239:53] is [239:56] a + b. Sorry after the closing quote. [240:03] Write comma. Now let's test the code. [240:07] Enter first number. Now I'm going to [240:10] enter one which is for addition. Okay. [240:14] We don't have any output. It should have [240:17] printed this addition. Okay. Okay. I got [240:20] the error. Now this one needs to be [240:23] surrounded by double quotes because [240:26] because as we already know by default [240:29] the input function treats all inputs as [240:32] string and a string must always be [240:35] surrounded by uh quotes like this. So [240:39] when I enter one it is treated as [240:41] string. So I'm comparing if choice which [240:45] is storing a string even though I'm [240:47] entering number but input function [240:49] treats it as a string. So I'm comparing [240:52] if string is equal to string. Now it [240:55] should work. So what if condition is [240:58] going to do? It will check if whatever [241:00] user enters equal to one or not. If user [241:03] does enter one then we are calling the [241:05] add function. [241:10] As you can see addition is 24. So let me [241:13] quickly walk you through this uh this [241:15] program again. So we have created two [241:18] two variables. First variable stores. [241:20] First number that user enters second [241:22] variable stores. The second number that [241:24] the user enters. Then we are displaying [241:27] this menu to the user. Right? And based [241:30] on this menu they can make a choice. Now [241:34] the choice variable is storing the [241:36] user's choice. Whatever choice user [241:39] makes. So here as you can see user [241:40] entered one. Now here I'm checking if [241:45] choice is equal to one which is true [241:47] because user did enter one condition was [241:50] evaluated to true and we called the add [241:53] function and we are passing the numbers [241:56] that user enters as arguments to the add [241:59] function and then here we are defining [242:02] the add function and receiving the [242:05] arguments then adding those numbers. Now [242:08] let's create functionalities for other [242:11] functions. If I enter two, as you can [242:14] see, we have no output because we have [242:16] not created function for the selection [242:20] two. So here we need to use obviously [242:23] else if if choice is equal to two. [242:28] Then we are going to create the multi [242:31] call the multiplication function. [242:34] multifunction pass [242:37] num one and [242:40] num two as arguments. Let's define the [242:45] multiplication function. [242:48] Define [242:51] multiplication [242:53] a b [242:56] print [243:00] multiplication is [243:04] a into b. [243:08] Let's execute the code. Let's select [243:11] two. As you can see multiplication is [243:13] 124. So it is working as it should. Now [243:18] let's check if user enters three. [243:23] I'm going to fast forward this and copy [243:25] the code. If user ch enters [243:29] three, then we are going to call the [243:32] division function [243:35] and pass the values that user enters as [243:39] arguments to the division function. [243:43] Let's create the division function. [243:53] Print division is division is [243:59] a divided by 2 b and let's see if it is [244:04] working [244:07] 3. Okay, division is 4.0. So it is [244:11] working just fine. And now let's create [244:15] function for the subtraction. If user [244:18] enters let's say [244:21] or [244:25] then we are going to call subtraction [244:27] function [244:29] and pass num one [244:34] and num two as arguments. [244:38] Let's create the function [244:42] subtraction. [244:46] Subtraction or difference is subtraction [244:50] is [244:52] a minus b. [244:56] Let's enter four. Okay. [245:00] Subtract positional parameter what were [245:02] given to at line number 23. [245:05] H subtraction. [245:10] Okay. [245:11] A B [245:15] now it should fix the error. Okay. [245:18] Subtraction is this. So it is working [245:21] perfectly. So guys we have created [245:23] functionalities for all four options. [245:27] Now what if user enters [245:31] five? [245:33] Right? We don't have any functionality [245:35] for five. So if user enters any other [245:38] option then we are going to [245:42] print an error message. Invalid choice. [245:47] Invalid choice. Now as we already know [245:50] the else statement is always written at [245:54] the end. Right? When you have else if [245:56] statements the else is always written at [245:59] the end. And when none of the conditions [246:02] match then the else gets executed. Let's [246:06] uh [246:08] execute the code. Let's enter six. As [246:11] you can see, invalid choice because this [246:14] value did not match to any of these [246:18] statements or if conditions, right? We [246:21] don't have any functionality for six. So [246:24] six did not match to any of these [246:27] conditions. So block of else was [246:29] executed where we are telling okay this [246:31] is an invalid choice. This program as [246:34] you can see it allows us to perform [246:38] these four operations. Now there is one [246:41] fundamental arithmetic operation missing [246:44] in this list that is the modulus. So [246:46] what you are going to do is add that [246:50] modulus functionality in your program. [246:53] Right? I intentionally left that out. [246:56] you are going to complete this by [246:58] yourself. So what you are going to do is [247:00] add the fifth item in this menu that is [247:03] going to be the modulus and create [247:05] functionality for that. It is simple [247:07] just add option five or fifth menu item [247:11] which will allow users to perform [247:14] modulus. Then down here you are going to [247:16] check if user selects five then you will [247:21] call the modulus function and and then [247:24] of course you have to define the modulus [247:26] function. That's the homework for you [247:28] guys and of course let me know if you [247:31] come up with any problems. [247:34] Lists are an essential concept in Python [247:37] programming. Lists in Python work the [247:39] same as arrays in other languages. A [247:42] list stores multiple values in a single [247:45] variable. As we already know, a regular [247:48] variable holds or stores only a single [247:51] value at a time. On the other hand, a [247:54] list can store multiple values within a [247:57] single variable. Therefore, a list [247:59] variable is a special type of variable [248:01] in Python where you can store multiple [248:04] values or items. A list in Python is an [248:08] ordered, mutable, and heterogeneous [248:11] collection of items or elements. Let's [248:14] break down each of these keywords one by [248:17] one. Ordered means list item maintain [248:21] their defined sequence and can be [248:24] accessed using index numbers in that [248:27] specific order. Okay, we'll explain it [248:30] in more detail shortly using practicals. [248:33] Okay, mutable means you can add, remove [248:35] or modify items in a list after it has [248:38] been created. Lists are also [248:41] heteroggenous. This means a list can [248:43] store different types of data. For [248:46] example, your list can have integers, [248:48] strings or decimal values in it. Now [248:52] let's dive into the practicals. Write a [248:56] a equal to. Now square brackets. Square [248:58] brackets are extremely important. A list [249:01] is defined using a square bracket. [249:04] Inside the square bracket, we we can uh [249:06] we can specify the items or values that [249:10] that you want to store. So let's uh [249:13] start with uh some numbers. [249:17] So we have successfully created this [249:20] list called a. This list as you can see [249:23] it is storing all these items. Now these [249:27] items are separated by commas. The list [249:30] items or values that you put in a list, [249:32] they must be separated by commas. Then [249:35] they will be considered as separate [249:37] values. So this is a single list [249:40] variable and we have stored 1 2 3 4 five [249:44] v values in it. So a single list [249:47] variable is storing five values. Let's [249:50] see how we can access a list. So print [249:53] a. Let's execute the code. As you can [249:57] see it is printing the entire list as it [250:00] is. Right? In this list we have these [250:03] many items and all of them have been [250:06] printed. Now I want to access individual [250:09] items. Right? Maybe I want to access 76. [250:12] 76 only not uh this entire list. So how [250:17] it is going to do that? Because we have [250:20] a single variable that is holding [250:22] multiple values. Well, Python uses [250:25] something called the indexing. Using [250:28] indexes, we can access individual items. [250:32] Now, the index values are assigned [250:35] automatically in the background by [250:38] Python. The first item is always [250:41] assigned index value zero. Second item 1 [250:46] 2 3 [250:50] 4. This is done automatically by Python [250:53] in the background. The first item has [250:56] index value of 0, second one, two and so [251:00] on. These are called index values. Now [251:03] let's say I want to access 76. Now what [251:06] is the index value of 76? Two. So using [251:10] its index value, I can access this 76. [251:14] Now in the print statement, write square [251:18] brackets. Within the square bracket [251:20] specify the index number that you want [251:22] to access. Let's say two. So write two. [251:26] And we should have 76. As you can see [251:30] 76. So that's how you create a list as [251:34] well as access them using their index [251:36] values. Now I want to access 787. [251:41] So again a [251:43] square brackets specify the index [251:45] number. 778 [251:48] is at fourth index. So four. [251:53] As you can see, we have accessed these [251:55] two items successfully. Using indexing [251:58] you can access any list item. So in a [252:02] list you can store as many items as you [252:06] like or values as you as you like. It [252:09] doesn't matter. These index values are [252:12] automatically assigned by the Python. [252:15] Just remember that the index values [252:18] always start from zero. First item in a [252:21] list will always have the index value of [252:23] zero. Second item 1, third, two, and so [252:28] on. Now let's create a list that stores [252:30] string values. Fruits, [252:33] let's say I have a list. fruit, [252:39] apple, [252:42] banana [252:44] and uh cherry. Okay. [252:48] So I have created another list called [252:53] fruit. This is a list variable and it is [252:55] storing these three values. Values must [252:58] be separated by a comma. So [253:03] now in a list whether you store string [253:06] values, integer, floats or even if you [253:09] mix them the indexing remains same. The [253:13] first item in a list will always have [253:16] the index value of zero. Second items [253:19] index value will always be one and so [253:22] on. Let's say I want to access banana. [253:25] So first I have to tell Python the exact [253:29] list name that you want to access fruits [253:32] then square brackets within square [253:34] brackets specify the index number I want [253:36] to access banana index value of banana [253:39] is one so we should have banana being [253:44] printed so that's how the the lists work [253:47] so in the next video we will learn how [253:49] to loop through a list. In this video, [253:53] we are going to loop through a list. [253:55] Previously, we learned that we can [253:57] access all list items at once or one by [254:01] one using indexes, right? However, in [254:03] many situations, we need to process [254:06] every item in a list automatically and [254:09] individually. This is where looping [254:12] becomes very useful. By looping through [254:14] a list, we can perform actions on each [254:17] element without writing repetitive code. [254:20] I will demonstrate it with with the a [254:22] real world example. Now let's dive into [254:26] the practicals. What I'm going to do is [254:28] uh create a list called files and it [254:32] will store some file names. uh let's say [254:43] okay so we have created this list called [254:46] files and it is storing these three [254:49] items or values they must be separated [254:52] by commas like this as you can see now [254:55] what I want to do is loop through all [254:58] the items that this list is storing I [255:01] want to access them one by one so write [255:03] for i in. Now specify the list name [255:07] where you want to loop through. For me [255:10] it is files colon [255:15] print I let's execute the code then I [255:19] will break down everything. As you can [255:20] see we are able to access all the list [255:23] items one by one. Now the way it is [255:26] working is this for loop will loop [255:29] through all the items one by one. The [255:32] important part here is this in keyword. [255:35] So the way in keyword works is it takes [255:38] each item from the specified list one by [255:41] one then store that item in the for [255:45] loops variable which is which is i. So [255:48] when this loop runs for the first time [255:50] the in keyword takes the first item from [255:54] this files list which is this then [255:57] stores that in the i variable. Down here [256:00] I'm printing the value of I. Value of I [256:03] is backup. So it is printing backup. [256:05] Then control moves back to the for loop. [256:08] Now in keyword automatically moves to [256:11] the next item in the list which is this. [256:14] It takes this list then stores it in the [256:17] I variable. So the old value that the I [256:21] variable is storing which is backup.py [256:24] gets overwritten by this new value [256:27] autoupd.py. [256:29] Now the current value of I is auto [256:31] upd.py. Then we are printing that here. [256:35] Then in keyword automatically moves to [256:38] the next item in the list demo. It takes [256:41] this item stores it in the I variable. [256:44] Then we are printing that here. As you [256:47] can see it has printed all the three [256:48] variables. And when there is nothing [256:52] more to iterate or loop through the loop [256:55] automatically exits. Okay. the control [256:58] moves out of the loop when there is [257:00] nothing or no more items to loop [257:03] through. So that's how the in uh works. [257:06] It takes one item from the provided list [257:10] one by one, then store those items in [257:13] the loops variable one by one. This way [257:16] we can access those items individually. [257:19] Now let's say I want to check if this [257:22] auto upd.py Pi file exists in this list [257:26] or not. It is easy. So what I'm going to [257:31] do is check if [257:34] I what is I? This I is this loops [257:38] variable which which stores these list [257:40] items one by one. So if I equal to let [257:44] me copy the exact thing that I want to [257:48] compare against. [257:52] print [257:54] item found in the list [257:59] and let's execute the code. As you can [258:02] see item found in the list. So the way [258:04] it worked is when this loop ran for the [258:08] first time the in keyword took the first [258:10] item backup.py stored it in the i [258:13] variable. Now the i is storing [258:15] backup.py. Here I'm checking if the [258:18] current value of i which is backup.py pi [258:21] is equal to auto upd.py. Now this [258:24] condition will not match because [258:27] backup.py is not equal to this. So block [258:31] of if will not be executed. And in the [258:34] next run the in keyword takes the second [258:37] value stores it in the i. Now value of i [258:40] is autoupd.py. [258:42] It checks if autoupd.py [258:45] is equal to autoupd.py. [258:47] This time these values match. So once [258:49] there is a match, Python executes the [258:52] code written uh inside this if statement [258:55] which is this. So it is printing this [258:58] message. Now let's uh try to check uh [259:01] auto upd 1.py. This time we don't have [259:05] any output because this file does not [259:08] exist in this list. It will not be able [259:11] to match this file against any of these [259:14] files specified in this files list. So [259:17] guys that's that's how you can loop [259:20] through lists. Looping through lists is [259:22] extremely important. This way we can we [259:25] can deal with each item individually one [259:28] by one. So to summarize the in keyword [259:33] acts as a membership operator and a [259:35] connector. It tells the Python to look [259:39] at a collection like a list or sequence [259:42] and pick out each item one by one. In [259:45] this video, we will learn how to [259:47] manipulate lists such as adding new [259:49] items to a list, removing items, [259:52] modifying existing items, and more using [259:55] list methods. Python provides plenty of [259:58] built-in methods or functions that allow [260:02] us to work with lists easily. These [260:05] methods let us perform various [260:07] operations on a list such as adding and [260:09] removing items, modifying existing [260:11] items, sorting ATC. Let's dive into the [260:15] practicals. Let me create a list [260:21] and I'm going to add these items to it. [260:24] Apple. [260:29] So I have this list called fruits and I [260:33] have uh included these items in it. We [260:36] are going to manipulate this list. I'm [260:38] going to start by appending or adding a [260:41] new item to this list. For example, I [260:44] want to add blueberry to this list. [260:47] Okay, the syntax is simple. First, write [260:50] the exact list name that you want to [260:53] update or where you want to append the [260:56] item to. For me, it is fruits dot. Now, [261:00] the method or function for appending [261:03] item to a list is simply appendp [261:08] within quotes. Write the item name that [261:11] you want to include. Let's say blue [261:14] berry. The way uh it is going to work [261:17] the Python will append this specified [261:20] item at the end of this fruits list. The [261:24] append function adds item at the end. So [261:29] let's print the complete list. [261:32] As you can see, blueberry has been [261:34] appended at the end of this fruits list. [261:37] The original fruits list did not have [261:40] the blueberry, right? But at line number [261:43] three, using the append method, we [261:46] appended this blueberry at the end. By [261:50] default, append adds at the end. Now I [261:53] want to add this blueberry at a specific [261:57] location, not at the end. In such case, [262:01] we have a method called insert. Okay, so [262:04] fruits do.insert. So I'm telling Python [262:07] that insert an item in this specified [262:11] list called fruits. Now inside the [262:14] inserts parenthesis we need to specify [262:18] two things. First the location where you [262:20] want to insert the item. I want to [262:23] insert after apple. Okay. So index value [262:27] of apple is zero. So if I want to append [262:31] after apple, the index value will be [262:33] one. So I'm telling insert at first [262:37] index add [262:43] blueberry. Make sure that index value is [262:46] separated by the comma. [262:50] As you can see we have successfully [262:52] added the blueberry at second position [262:54] or at the index value one. This way you [262:58] can add at any location. Let's say [263:02] three. [263:04] As you can see, we have added at the [263:07] third index 0 1 2 and three. At third [263:12] index, we have added the blueberry. Now, [263:15] let's see how we can remove uh items [263:18] from a list. [263:20] So first obviously we need to provide [263:23] the list name where you want to remove [263:26] the item fruits dot [263:30] remove. [263:32] Now within quotes specify the item name [263:36] that you want to remove. I want to [263:38] remove cherry [263:40] cherry. So remove method is going to [263:43] remove this cherry item from the list. [263:47] If if this item does exist in this [263:50] specified list, it will remove this [263:52] cherry from this list. As you can see, [263:55] cherry has been removed from the list. [263:59] Right? This way you can remove any item, [264:02] right? Just specify the exact list value [264:05] that you want to remove. This time it [264:07] will remove apple from this fruits list. [264:11] As you can see, apple has been removed. [264:13] We have another method for removing [264:18] items which is pop. So fruits dot pop. [264:22] As you can see it has removed papaya. By [264:24] default the pop method removes the last [264:28] item from a list. Right? In this uh list [264:34] called fruits the last item is papaya. [264:36] So pop method removed it. That's how it [264:40] works. Now we can also remove list items [264:43] by their index values. For example, I [264:46] want to remove cherry. The index value [264:48] of cherry is 0 1 2. So within brackets, [264:52] specify two. It will remove the cherry. [264:55] As you can see, cherry is no longer in [264:58] the list. Let's remove zero. At zero, we [265:01] have apple. It should remove apple. Now [265:06] I want to remove all the items from a [265:10] list. So write the list name fruits [265:15] dotclear. Now the clear method clears or [265:19] removes all the items from a list. So [265:22] here I'm applying this clear method to [265:25] this fruits list. So it will remove all [265:28] the items from this fruits list. As you [265:32] can see now we just have an empty list. [265:35] Right? Another method that we have is [265:39] called index. Now the index method [265:42] returns index value of the specified [265:46] item. So here I have provided apple item [265:50] to this index method. So it will return [265:53] the index value of this item. We are [265:57] going to store that index value here. A [265:59] equal to fruits dot index. Uh let's uh [266:04] print A. [266:06] As you can see zero apple is at zero [266:10] position. So the way it worked is the [266:13] index took the index value of apple then [266:16] we are assigning that value to a and [266:19] down here we are printing that value. [266:22] Let let's go for let's say cherry [266:27] and we have two cherry is at second [266:30] position 0 1 2 right so that's how the [266:33] index works [266:36] then we have uh something called [266:39] count the count method counts how many [266:42] times an item is appearing in a list for [266:46] example apple right so count method is [266:50] going to count how many times times the [266:52] specified list item apple is present [266:55] inside the a fruits list. Again we need [267:00] to assign the value to a variable. So [267:04] count equal to this [267:11] as you can see one. So the way it worked [267:13] is count method counted how many times [267:16] uh the apple is appearing in this fruits [267:20] list. then stored that value in the [267:24] count variable. Down here we are [267:26] printing the value of count which is [267:28] holding how many times apple is uh [267:30] present in this list. We have one as an [267:33] output. As you can see apple is present [267:36] exactly one time. Now let's add another [267:39] apple to verify [267:42] uh the working of count apple [267:45] and we have two right. So apple is [267:48] present two times in this list. Now [267:51] let's see how we can copy a list. We [267:54] have this fruits list. Right? Now I want [267:57] to copy this list or I want to copy all [267:59] its items. So let's see fruits backup [268:05] equal to. Now write the list name that [268:09] you want to copy. I want to copy fruits. [268:13] Then copy. [268:16] Let's print [268:19] fruits backup. [268:22] As you can see, we have copied it [268:24] successfully. So the way it worked is [268:27] I'm providing fruits list to the copy [268:30] method. So copy method is going to take [268:32] all the items from the fruits or [268:36] provided list then store those items uh [268:39] in this variable fruits bk as list. [268:42] Okay, it will copy all the list items [268:45] then store them into this new list [268:48] variable fruits BK. Down here I am uh [268:52] printing the fruits BK variable, right? [268:55] As you can see, it is holding the exact [268:58] values that are present in this original [269:01] fruits list. So that's it. Okay. Okay, I [269:03] almost forgot the sort method. Before [269:06] signing off this video, uh let's see how [269:09] we can use the sort method. Fruits dot [269:14] sort. Okay. Now, the sort method sorts [269:19] the list items in ascending order from A [269:23] to Z or lower to higher. As you can see, [269:27] roots. Okay, we have an error. Fruits BK [269:30] is not defined. Okay, fruits. Fruits. [269:35] As you can see, it has sorted these [269:38] items in the ascending order. Okay, [269:41] let's add let me remove the apple [269:45] and add [269:48] maybe zen. [269:53] So sort uh method is going to sort these [269:56] items in ascending order from A to Z. As [269:59] you can see, even though this list [270:01] doesn't have sorted items, but after [270:04] applying the sort method, it has uh [270:07] sorted the list from A to Z. [270:13] It can also sort numbers. Uh let's [270:16] provide [270:22] as you can see it has sorted these [270:24] numbers that are in this list. So that's [270:26] how the sort method works. Now let's see [270:31] how we can uh sort items in reverse [270:34] order from highest to lowest. Fruits dot [270:40] sort. [270:42] Now within parenthesis write reverse [270:44] equal to true. Make sure that t of true [270:49] is in uppercase. [270:51] As you can see it has sorted in [270:54] descending order. So that's it for this [270:56] video. Tupils are a data type similar to [270:59] lists used to store multiple items in a [271:02] single variable. However, the main [271:04] difference between a tupole and a list [271:07] is that tupils are immutable. Meaning [271:11] you can't change, add or remove elements [271:14] after the tupil is created. uh tupils [271:18] are often used when you want to store a [271:21] fixed set of values that should not be [271:24] modified or updated. The second [271:27] difference is that tupils are defined [271:29] using parenthesis whereas lists use [271:32] square brackets. Right? Now let's dive [271:35] into the practicals. I'm going to create [271:37] a simple tupal. So a equal to [271:40] parenthesis. The tupils are defined [271:44] using the parenthesis. Inside the [271:47] parenthesis, you can place your values [271:51] 12. [271:54] Now the values or items must be [271:57] separated by commas like this. So we [272:00] have uh successfully created the tupal [272:03] called a and it is storing all these [272:07] different values separated by by commas. [272:10] Right now let me print [272:13] the tupil a and we have accessed all the [272:17] tupal items over the entire uh tupil. As [272:20] you can see here just like uh lists the [272:24] tupil are indexed means tupal items can [272:28] be accessed using index their index [272:31] values. Right? The first item in a tuple [272:35] is automatically assigned the index [272:38] value 0 second 1 2 3 and so on. Now if [272:44] you want to access let's say 56 then we [272:48] need to use its index value which is [272:51] two. So after the tupal name which is a [272:55] square brackets within square brackets [272:57] specify the index index number two. At [273:00] index number two we have 56. So it will [273:02] print 56. As you can see this way you [273:06] can access any tupal item using um using [273:11] its index value. Let's access tupal [273:14] item. Fourth item. At fourth item we [273:18] have 787. [273:21] And yeah that's how you can create and [273:22] access tupils. [273:25] Now uh let's see how we can loop through [273:28] a tupole. Looping through a tupole is [273:30] same as we looped through a list. Right? [273:34] For i in now specify the tupal name that [273:38] you want to loop through. For me it is [273:40] a. Now print uh value of i. [273:47] As you can see we have successfully [273:48] accessed all the tupal items. Right? The [273:52] way it is working is when this loop runs [273:56] for the first time, the in keyword takes [274:00] the first item that is stored in the [274:02] tupal 12 and stores it in the variable [274:06] i. Then we are printing that out. [274:09] And on the second run, the in keyword [274:13] takes the second value store that in the [274:16] i variable. So we are printing I which [274:20] is the second value is this and on the [274:23] third run the in keyword takes the third [274:26] value stores it in the i variable then [274:28] we are printing that here. So this for [274:31] loop keeps repeating as long as there [274:34] are items in the tupole. So when there [274:36] is nothing to iterate or loop through [274:39] the loop automatically exits or [274:42] terminates. Now guys, like I mentioned [274:44] earlier, tupils can't be updated or [274:46] modified, right? So if you want to [274:49] modify a tupole, then we need to do the [274:53] type casting that we will discuss in the [274:55] next video. In this video, we will take [274:57] a look at the tupole methods in Python. [275:01] Unlike lists, tupils don't have [275:04] dedicated methods for updating or [275:06] removing items because tupils are [275:09] immutable, meaning they can't be changed [275:12] after they are created. You can't add or [275:15] remove items in a tupole. However, there [275:18] are situations where you may need to [275:22] modify or update the data stored in a [275:25] tupole. Since you can't directly add, [275:27] remove or change items inside a tupole [275:30] as you would with a list, you need to [275:33] use a workaround. Let's see how we can [275:35] update, modify, or manipulate a tupole. [275:39] The only way to manipulate or modify a [275:42] tupole is we need to convert it into a [275:46] list. So once it is converted into a [275:48] list then we can use list methods to [275:51] manipulate it and then convert the list [275:55] back to the tupole. Right? So here I [275:58] already have this tupil here that is [276:00] storing these items. Now [276:04] I want to add a new item to this tupal. [276:08] So step one we need to convert it into a [276:11] list. So a equal to list. Now list is a [276:16] function that is used to convert other [276:19] data type into a list. Now within [276:22] parenthesis specify the tupil that you [276:25] want to convert into a list. Let me put [276:27] a. Now what is a? A is a tupal right? So [276:32] list is going to take this tupil convert [276:34] it into a list then store that in a. Now [276:38] a is storing the tupal that has been [276:41] converted into a list. Now it it has [276:44] become a list. So let's quickly check [276:48] its type. [276:53] As you can see now a is a list. If I use [276:58] this print statement above the list [277:01] function [277:03] as you can see tupil. At line number two [277:06] we are printing type of a. Here it is [277:08] tupil. But at line number three I [277:10] converted this tupil into a list. Now it [277:14] is a list. Now once we convert it into a [277:17] list, now we can [277:20] perform any operation that we want. For [277:22] example, I want to insert a new item at [277:26] index 2 item after 44. So insert [277:33] 3 [277:35] 78 [277:36] print a. [277:40] As you can see, I have inserted an item [277:43] at the third index, right? 0 1 2 3. At [277:49] third index, we have 78. This way, you [277:52] can perform any any modification or [277:56] manipulation with a tupal. Okay, you can [277:59] use any list method that we that we [278:02] want. Now, after modifying the list, I [278:05] want to convert it back to the tupal. So [278:09] a equal to [278:11] tupal. Now the tupal function converts [278:14] other data type like uh like list into [278:18] uh tupal. So a now I have provided it [278:22] the a. What is a? A is storing this [278:27] list. Right? Now here I I converted this [278:30] tupil into a list. Right? So a is now a [278:33] list. Now down here after performing [278:36] this insert operation I'm converting [278:39] this a which is a list back to the [278:42] tupole storing that tupil in the [278:44] variable a. Now let's uh print the a. As [278:48] you can see it is it has been converted [278:51] back to the tupole. So guys that's how [278:54] you can modify a tupil. That's the only [278:57] way to modify a tupole. we need to [279:00] convert it into a list then perform the [279:02] desired operation then convert it back [279:05] to the to the tupal. So yeah this is as [279:09] simple as that. Now let's explore a few [279:11] more [279:14] tupal methods. [279:18] Now the length method is used to to get [279:22] length of a tupil. As you can see we [279:25] have four to length function. I have [279:27] provided the tupal which is a. So what [279:30] length function does it counts how many [279:32] items are there in a tupole. So in this [279:36] tupal we have four items. So we have the [279:39] output four. In this video we will learn [279:43] about dictionary methods in python. A [279:45] dictionary provides many built-in [279:48] methods that allow us to manipulate data [279:51] efficiently. Using uh dictionary [279:53] methods, we can add new items, remove [279:56] existing items, access keys and values [279:59] separately, update data and perform many [280:02] other common operations on dictionaries. [280:05] Now let's dive into the practicals. I [280:07] have already created this uh dictionary. [280:10] I will be manipulating and updating this [280:13] dictionary. I'm going to start with the [280:15] clear method. Clear method basically [280:18] removes all the items from a dictionary. [280:21] So write user the dictionary name where [280:24] you want to perform this operation dot [280:28] clear. [280:30] Now let's print [280:32] the dictionary name user. So what clear [280:34] method does? It takes all the items from [280:38] the dictionary that you specify which is [280:40] user for me then removes all of them. [280:43] Okay. Now let's execute the code. As you [280:46] can see here, we have an empty [280:48] dictionary, right? This user dictionary, [280:51] it was emptied by this clear method. It [280:54] removed all the elements from it. Now, [280:57] next method that we have is copy. Let's [281:00] say I want to make a copy of this uh [281:03] user dictionary. It is also simple. [281:07] Create a dictionary variable where you [281:10] want to copy the contents of a [281:13] dictionary. Let's say user [281:16] backup [281:20] equal to now I want to copy this user [281:23] dictionary. [281:25] Write the name of the dictionary that [281:27] you want to copy. User dot [281:32] copy. The copy method is going to take [281:34] contents of this specified dictionary [281:38] and put that into this specified [281:40] variable. So let's print this user back [281:44] up variable dictionary variable to be [281:48] specific. [281:50] As you can see I have successfully [281:52] copied contents of this user dictionary [281:55] into this user [281:58] backup dictionary variable where I'm [282:00] printing its content. [282:03] Now next thing that I want to do is I [282:05] only want to access the keys right keys [282:10] like name, ID and salary. I don't want [282:13] to print their values only the keys. The [282:17] method for accessing only keys is keys. [282:22] So write the dictionary name whose uh [282:26] keys you want to print dot now write [282:30] keys parenthesis. Now the keys method [282:34] returns only the keys. Let's execute the [282:37] code. As you can see it has returned [282:40] keys, right? Name, ID, salary, right? [282:42] These are the keys. Now in the next [282:45] video I will demonstrate in detail how [282:48] to loop through keys values separately. [282:52] Okay, for now I just want to to [282:55] demonstrate methods how they work. [282:59] Now next thing that I want to do is I [283:02] only want to access values not the keys. [283:06] Okay, the method for accessing only [283:10] values is simply values. Let's execute [283:14] the code [283:16] and as you can see it has returned only [283:20] the values timalu,00 and 100,000. Right? [283:23] These are the values. Okay. Like I said [283:27] in the next video I will demonstrate how [283:29] to loop through loop through keys, [283:31] values and both. Okay, the next method [283:35] is something called items. Now item [283:37] method returns both keys and values. [283:41] Okay. Uh let's execute the code. As you [283:44] can see it has returned all the pairs [283:47] keys and values or the complete pairs. [283:50] As you can see this is the first pair, [283:52] the second pair and third pair. Next [283:55] thing that I want to do is update this [283:58] dictionary. I want to add more details [284:02] to this user dictionary. It is simple [284:06] user dot update we have the update [284:10] method. Uh in dictionary that we can use [284:13] for updating dictionaries. [284:17] Then within parenthesis write the curly [284:19] braces. Within the curly braces we need [284:21] to specify the details. For example, [284:24] let's say address. I want to add address [284:27] colon [284:31] let's print the updated dictionary. Now [284:35] the way update method works is it [284:38] inserts uh the pair at the end of uh a [284:43] dictionary. So let's uh execute the [284:46] code. As you can see the address pair [284:48] has been appended or added at the end of [284:51] this dictionary. We can insert multiple [284:55] pairs as well or as many pairs as you [284:57] like. Just separate them with a comma [284:59] like this. Now let's uh in uh add [285:03] another detail that is going to be [285:06] designation [285:10] programmer. Let's execute the code. As [285:14] you can see guys, both of these pairs [285:18] have been uh added to this user [285:21] dictionary, right? And again, the new [285:24] pairs or details that you add to a [285:27] dictionary, they are always appended at [285:30] the end of a dictionary like this. Now [285:33] let's see how we can merge two [285:35] dictionaries into one. So we we already [285:39] have a dictionary called user. Now let's [285:42] create another dictionary called user 2 [285:52] coder. Okay. So we have these two [285:55] dictionary right dictionaries right user [285:57] and user two. I want to merge them. It [286:00] is simple. First write the dictionary [286:03] name where you want to merge another [286:06] dictionary. So I want to merge user [286:10] dictionary into user 2. So user dot [286:14] update [286:16] within the [286:18] parenthesis specify the dictionary that [286:20] you want uh to merge. So the way it is [286:23] uh going to work, Python is going to [286:26] take all the key and value pairs from [286:29] this user to dictionary then merge them [286:34] with the dictionary that you specify at [286:37] the beginning. Okay, the contents of [286:40] this dictionary will be appended or [286:42] added at the end of this user [286:44] dictionary. So here I'm uh down here I'm [286:47] printing the user dictionary, right? So [286:49] let's uh execute the code. As you can [286:52] see, we have successfully appended or [286:55] merged this user to dictionary with [286:58] user. Right? Now, when you update or [287:02] merge two dictionaries, the Python [287:04] doesn't modify or alter the dictionary [287:07] that you are merging to. For example, [287:09] user two. I'm merging user two with the [287:11] user. So, if I print simply the user [287:14] two, [287:16] as you can see, its details are intact. [287:19] So that's how you can update your [287:21] dictionaries. Another method uh that uh [287:24] we can use is length len. [287:28] Let's execute the code. Okay, we have an [287:30] error. User two is not defined. I think [287:33] it's user just user. [287:38] As you can see we have three. So length [287:41] method it returns the total pairs in a [287:44] dictionary. In user dictionary I have [287:47] total three pairs. So we have output [287:50] three right now. Let's see how we can [287:53] remove or delete dictionary items. So [287:58] user [288:00] dot pop item. Now the pop item method [288:05] removes the last pair in a dictionary. [288:10] In this dictionary the last pair is [288:12] salary. So here uh I'm specifying the [288:15] dictionary user then dot pop item. So [288:18] pop item is going to take the last pair [288:21] from this last pair from the user [288:24] dictionary and then remove it. Let's [288:26] execute the code. What? Okay. Okay. I [288:31] need to remove the length function. [288:35] As you can see guys, the last pair which [288:38] is salary is missing because it has been [288:40] removed by the pop item. Now uh the pop [288:45] item has one limitation. It only removes [288:48] the last item or pair in a dictionary. [288:51] Now I want to remove a specific specific [288:55] pair. For example, I want to remove [288:57] maybe ID. So user dot pop [289:03] within co within quotes specify the key [289:07] that you want to remove. I want to [289:09] remove ID. So we need to specify the [289:12] exact key name. Now the pop method is [289:15] going to remove this key ID and of [289:18] course its value as well. So it will get [289:21] rid of this particular pair. [289:26] As you can see the ID is missing, right? [289:29] It has been removed. Let's remove name [289:31] as well. Now this time it should remove [289:34] the name as you can see. So that's [289:37] pretty much it for this video guys. In [289:40] this video we are going to learn how to [289:42] loop through a dictionary in Python. [289:44] Dictionaries store data in key value [289:47] pairs. Right? And Python provides [289:49] several useful ways to access this data [289:52] using loop. So we can loop through just [289:54] the dictionary using keys method or we [289:58] can loop through just the values using [290:01] the values method. And of course we can [290:04] loop through both using the items [290:08] method. These built-in dictionary [290:10] methods make it easy to work with [290:13] dictionary data efficiently and clearly. [290:16] Now let's dive into the practicals and [290:18] see how we can loop through a dictionary [290:22] efficiently. [290:23] So write uh for uh and of course I have [290:27] already created this dictionary that [290:30] contains these pairs. So I'm going to [290:32] loop through them. So for i in now [290:38] specify the dictionary name that you [290:40] want to loop through. For me it is user [290:44] user. Now I only want to access the [290:49] keys. I only want to loop through the [290:51] keys. So to access only keys we have [290:56] method called keys, right? So keys, [291:00] right? Like this [291:03] print [291:05] I. Now as we already know the keys [291:08] method returns only the keys like name, [291:12] ID and salary. So for loop is going to [291:14] loop through all the keys one by one. [291:18] When this loop runs for the first time, [291:20] the value of this for loops variable [291:23] will be name. This is the first key, [291:28] right? So it will print name. And when [291:31] this loop runs for the second time, then [291:34] the value of I becomes ID, which is the [291:36] second key. Then we are printing that [291:39] here. Let's execute the code. As you can [291:42] see we have the expected output right. [291:45] So now again the keys method returns all [291:48] the keys. So for loop is going to take [291:50] each key one by one then store uh that [291:54] key in the for loops variable. Then we [291:56] are printing that out here. Right? [291:59] Similarly you can access uh values like [292:02] demalu [292:04] 100,000. So as we as we already know the [292:09] method for accessing uh values is simply [292:13] values. [292:16] As you can see we have successfully [292:18] accessed the values right. So value [292:21] method returns values. For loop is going [292:24] to loop through each value one by one. [292:27] So when this loop runs for the first [292:29] time the value of i becomes the first [292:32] value which is dimo. So we are printing [292:35] this and on the second run value of i [292:39] becomes uh 1,000. So we are printing [292:41] that as well. On the third run value of [292:43] i becomes this. So it is being printed. [292:46] And when there is nothing more to loop [292:49] through the loop automatically exits or [292:53] it gets terminated automatically when [292:55] there is nothing to loop through. Now I [292:58] want to access or loop through both at [293:02] the same time keys as well as their [293:05] associated values. Now the method for [293:08] that is items. Right? [293:12] Now in the for loop we need to define [293:15] two variables. One variable will store [293:18] key and the second variable will store [293:20] value. So key, [293:24] value. [293:25] So item method returns both key and [293:28] value. Now the first variable that you [293:30] specify in the for loop, it is going to [293:33] store the key. The second variable is [293:35] going to store the the value. So key [293:41] comma value. I'm printing both key and [293:44] value variables as you can see. Let's [293:47] execute the code. As you can see name [293:50] demalu ID 1,00 and sales. So the way it [293:55] is working the item method returns both [293:59] keys and values right. So when this loop [294:01] runs for the first time the for loop [294:04] takes the first value which is uh key [294:08] stores that into the key variable then [294:11] it stores the value in the second [294:14] variable which is value. So down here we [294:16] are printing both key and value. It [294:19] repeats this for all the pairs. when it [294:23] loops through all the pairs then loop [294:25] automatically exits. So guys, that's how [294:28] you can access or loop through keys, [294:30] values, or both. So that's pretty much [294:34] it for this video. A set in Python is a [294:36] built-in data structure used to store [294:39] multiple unique values in a single [294:41] variable. It is an unordered collection [294:44] of unique items. It is it is unordered, [294:48] mutable, and doesn't allow duplicate [294:50] items. So let's break down these [294:52] characteristics. Unordered simply means [294:55] items have no fixed position. Sets do [294:57] not use indexing like lists or tupils. A [295:01] set in Python is mutable which means you [295:03] can change it after creation by adding [295:06] or removing elements. However, you can't [295:08] modify individual elements directly [295:11] because sets are unordered and don't [295:14] support indexing. The best thing about [295:16] sets is that they don't allow [295:18] duplicates. they automatically remove [295:21] duplicates. Now let's dive into the [295:24] practicals and create a set. So a equal [295:27] to curly brackets or curly braces. A set [295:31] is created using the curly brackets just [295:35] like the dictionaries. However, a set [295:37] doesn't contain key and value pairs. [295:40] That's the differentiating factor. Let's [295:44] add a few elements to it. [295:48] We have successfully created the set [295:50] called A and it contains these four [295:54] elements and the set elements must be [295:57] separated by commas like this. Now let's [296:00] see how we can access a set. Print a is [296:06] uh a set as you can see [296:08] and we have the output as you can see we [296:11] have successfully accessed the set and [296:14] all its items. However, you might notice [296:18] uh something unusual here. This output [296:22] is a bit uh different, right? The set [296:25] items are not appearing in the same [296:27] order as they are created or assigned. [296:30] This is because sets are an unordered [296:33] collection. They are not organized in [296:36] indexes. Therefore, a set doesn't return [296:39] its elements in the same order as they [296:42] are created. So they will appear in [296:44] random order whenever you access them [296:47] like this. So this is completely normal. [296:50] So don't get confused here. Now let's [296:52] say I want to access an individual [296:55] element. For example, I only want to [296:57] access 56. Well, we can't do that with [297:01] sets. Like I like I said, sets are not [297:05] organized in indexes. Therefore, we [297:07] can't access them individually. So to [297:09] access sets individually we have to loop [297:13] through them for i in a a is a set. So [297:20] what I'm doing here [297:22] I'm looping through the set a. So for [297:26] loop is going to take one element on [297:29] each run then assign that element to the [297:32] variable i. Down here we are printing [297:34] the value of i. Right? [297:37] As you can see, we have successfully [297:39] accessed all the items. So when this [297:41] loop runs for the first time, the for [297:44] loop takes the first element from this [297:46] set, then stores that in the variable I. [297:49] Down here we are printing that variable. [297:52] Uh then it moves to the next element, it [297:54] takes this element, stores it in the I [297:57] variable, then we are printing that [298:00] variable. So it keeps repeating this [298:03] process until there is nothing more to [298:06] loop through. Just like the lists, [298:08] tupils and dictionaries. Right? So [298:11] that's how you can access individual set [298:13] elements. Now one of the best features [298:16] of a set is that they do not allow [298:20] duplicates. Right? As you can see for [298:22] now this list doesn't contain any [298:24] duplicate items. Let's add a duplicate [298:28] item 12. [298:31] Print a. Now the 12 as you can see we [298:34] have the duplicate of 12 here. Let's [298:37] print a and as you can see it has [298:41] automatically removed the duplicate item [298:44] 12. Right? It automatically removed the [298:47] duplicate item 12. So a set [298:50] automatically removes all duplicate [298:52] items. [298:56] In this lesson, we will cover the most [298:58] important set methods in Python and how [299:01] to use them to add and remove elements [299:04] and perform operations like union, [299:07] intersection, ATC. So in short, we will [299:09] be manipulating a set. So let's dive [299:12] into the practicals. Let's dive into the [299:15] practicals. I already have uh this set [299:18] and we are going to manipulate this set. [299:21] I'm going to start by adding a new [299:24] element to this uh set. Let's get rid of [299:28] this duplicate item. [299:30] A write the set where you want to add uh [299:34] the element to dot the method for adding [299:37] a new element is simply add. Uh let's [299:40] say I want to add uh 333. Let's print [299:45] the set. And uh as you can see the the [299:51] 333 has been added to this set. When you [299:55] add a new element to a set, it is not [299:58] inserted at a specific location because [300:02] uh like I like I mentioned in the [300:04] previous video, a set is not organized [300:06] in an indexes, right? So a new element [300:09] gets inserted in any position. So that's [300:13] the add method. Now we can also add [300:17] multiple elements to a set right we [300:20] can't do uh that with the add method [300:24] like this it will throw an error [300:27] as you can see. However we have the [300:31] update method for that update method [300:34] allows us to uh add multiple elements to [300:37] a set. Now update brackets within [300:40] brackets. You can specify the elements [300:43] that you want to add. They must be [300:46] separated by a comma. This time I am [300:49] inserting these three elements to the [300:51] set. A let's execute the code. As you [300:54] can see all the three elements have been [300:57] added to this set. This way you can add [301:00] as many elements as you like. Like like [301:02] this just separate them with commas. Now [301:07] next uh method that uh we have is clear. [301:10] Now the clear method clears uh a set. So [301:15] it will remove all the all these [301:17] elements from the set and we will have [301:20] an empty set. As you can see set we have [301:24] an empty set with no elements. Now let's [301:26] see how we can remove [301:30] or delete elements from a set. [301:33] a dot pop. Now the pop method removes [301:38] one item from a set and that item can be [301:42] anything. It removes a random item. [301:45] Okay, as you can see uh here it has [301:47] removed 56, right? It is no longer here. [301:51] Now the obvious limitation of the pop [301:53] method is that it removes a random item [301:57] where you can't specify your choice [301:59] which uh item you want uh exactly to [302:02] remove. So if you want to remove a [302:05] specific item then we have the remove [302:07] method. Sorry remove [302:09] within parenthesis specify the exact [302:12] item that you want to remove. Let's say [302:14] 56. So [302:17] 56 and as you can see we have removed [302:20] the 56. Let's remove 550 uh 61. As you [302:26] can see, we have an error, right? [302:28] Because this [302:30] element that I am attempting to remove, [302:34] this doesn't exist inside this set. So, [302:38] we have an error. Now, let's remove [302:40] four. The four is indeed in my set. So, [302:45] it will remove four, right? As you can [302:47] see now we have a similar method to to [302:51] remove which allows us to remove a [302:55] specific item or item of your choice [302:57] that is discard. Discard like this write [303:01] discard. Let's say I want to remove 12 [303:05] and it will remove the specified element [303:07] which is 12. As you can see it is no [303:08] longer in the list. Now let me attempt [303:11] to remove 1255. [303:15] As you can see guys, this time we have [303:18] no error. The difference between discard [303:20] and remove is that if the element that [303:23] you want to remove doesn't exist, it [303:26] will not throw an error. But the remove [303:30] method if the item doesn't exist, it [303:33] will [303:34] throw an error as you can see here. But [303:38] the discard method doesn't exist, [303:40] doesn't throw an error. If the element [303:44] that you are attempting to remove [303:46] doesn't exist, it simply returns the [303:50] set. As you can see, now let's move on [303:53] to the intersection method which is very [303:57] important. So B equal to let's create [304:00] another set 45 [304:04] 4 [304:06] 12. So we have these two sets right with [304:09] four elements each. Now let's apply the [304:13] intersection method to it. So C equal to [304:19] intersection [304:21] B A dot intersection. So a dot [304:26] intersection then within parenthesis we [304:29] have specified the second set b. So what [304:31] intersection basically does it takes the [304:34] common elements from both the sets that [304:37] you specify. Here I have specified uh a [304:40] and b. I'm telling the intersection [304:43] method that take the common elements [304:47] from A and B then assign those to the C [304:53] variable or set variable. So C variable [304:55] is going to store the common elements in [304:59] both of these sets. So print C. [305:03] Let's execute the code. As you can see [305:06] we have 12 and four. Now these are the [305:10] common elements in both of these sets [305:14] right 12. We have 12 here and 12 here as [305:17] well. We have four in the A and four [305:20] also in the B. So the intersection [305:23] method returns the common elements from [305:27] both the sets that you specify here. [305:30] Okay. Now let's move on to the union [305:33] method. So a dot [305:37] union [305:39] within parenthesis write b. Now the [305:41] union method is used to combine all [305:45] unique elements from two or more sets. [305:48] In other words, duplicate duplicates are [305:51] removed automatically. It is one of the [305:53] most common set operations because it [305:55] allows you to merge data and also it [305:59] ensures there are no duplicates in the [306:01] final results. Okay, so let's execute [306:04] the code. As you can see guys, it [306:06] combined these two elements, but it [306:09] removed duplicates. It did not include [306:12] the duplicates. In these two sets, we [306:14] have 12 which is present in both of [306:17] these sets A and B. It did not include [306:21] duplicates. We have four which is [306:23] common. In these two sets, it also did [306:26] not include the four. It automatically [306:29] removed the duplicates. So it took [306:31] unique elements from these two sets then [306:35] combined them and stored the combined [306:37] list into the new variable C. So C is [306:41] storing the unique elements from these [306:44] sets then we are printing that here. So [306:47] that's pretty much it for this video [306:49] guys. There are a few more set methods [306:52] that we will cover in an upcoming [306:55] sections. They are not relevant for now. [306:57] So thank you very much guys. [307:00] In this video, we are going to take a [307:02] look at two important functions, split [307:05] and join. These functions are commonly [307:08] used when working with lists and [307:11] strings. We will explore how they work, [307:14] when to use them, and how they can help [307:16] us manipulate text data more [307:19] efficiently. Now, let's dive into the [307:21] practicals. Let me quickly create a [307:23] string root admin user. Now I want to [307:28] take this string and put these three [307:32] words in a list as separate list [307:35] elements. So type x. Now specify the [307:39] string or variable that you want to [307:42] convert uh into a list dot. Now specify [307:46] the [307:47] split. Split method basically converts a [307:50] string into a list. Now within the [307:53] parenthesis of split specify a [307:56] delimiter. Delimiter means how your [307:59] string is separated. For example in my [308:02] string as you can see these words are [308:04] separated by a spaces right. So specify [308:07] the space. So the way split uh function [308:10] works is let me first print x. [308:16] As you can see guys, we have [308:17] successfully converted this name string [308:21] into a list. So split function converted [308:25] this name string into a list stored uh [308:30] that in the x variable. Then we are [308:32] printing the variable x. Let's see how [308:34] it is working. So the way split uh works [308:37] is it scans your string and checks for [308:41] the for the specified delimiter which is [308:45] space. I have specified space right. So [308:47] here when it scans this string okay it [308:49] checks root then this root is separated [308:53] by a space. As you can see here root is [308:56] separated by space. There is a space [308:58] between root and admin. So wherever it [309:00] finds a space it takes that word then [309:04] puts that in a list item. As you can see [309:08] it is a separate list item. Then we have [309:11] admin. Now admin is also separated by a [309:14] space right as you can see there is a [309:16] space between admin and user. So it also [309:19] takes this and puts it as a separate [309:22] element in a list. So in this list we [309:25] have three list elements or items. So [309:29] that's how the delimiter works. Now what [309:32] if your [309:34] string is separated by commas like this. [309:40] Now here as you can see we have a [309:41] visible difference. Now in this first [309:44] list we have three separate list items. [309:46] However in this list there is only one [309:49] list item because here separator is [309:52] comma. Right? These three words are [309:54] separated by comma. However we have [309:56] specified the delimiter or separator [309:59] space. So this space doesn't match the [310:03] commas that are separating these three [310:06] words. Now if your string is separated [310:10] by commas then we need to specify the [310:14] comma as well in the split method like [310:16] this. As you can see now we have three [310:20] separate list elements. Right? So that's [310:23] how you can uh convert [310:27] a string into a a list. So split method [310:33] takes the name convert it into a list [310:36] then stores that list in the x variable. [310:40] Uh down here we are printing the [310:42] variable x. This way you can convert any [310:44] string into a into a [310:48] list. We just need to specify the [310:51] separator. How uh items in your string [310:54] are separated. That that's pretty much [310:56] it. Now let's dive into the join method. [311:00] join method is opposite of the of the [311:04] splitter. It takes a list then convert [311:08] that list into a string. Okay. So let's [311:11] create a list. [311:14] Let's say we have the name [311:17] names root [311:21] admin [311:23] auto. So in this list we have these [311:26] three uh three list elements right I [311:31] want to convert this list into a string [311:33] I want to take these three separate list [311:37] elements and put inside a string let's [311:40] say full name equal to [311:44] first we need to specify the separator [311:47] how you want to separate these elements [311:51] so I want to separate them with a comma [311:53] Uh now sorry not comma space a space [311:58] right then dot join [312:03] and provide the list to the join method [312:07] like this let's execute the code okay [312:11] looks like uh we have an error name is [312:14] not defined okay the list name is names [312:18] here I have specified name let's print [312:24] full name and uh execute the code. As [312:27] you can see guys, we have successfully [312:29] converted a list into a string. So the [312:32] join method took all the elements stored [312:36] in the names list which are these then [312:41] converted them into a single string and [312:44] then stored the converted value in the [312:47] full name variable. Down here we are [312:49] printing the variable. Now here uh we [312:52] have this space delimiter which simply [312:55] means how you want to to separate your [312:58] list elements. We have specified space. [313:01] So we have space uh between our list [313:04] elements. What if I specify let's say [313:06] maybe comma then these elements will be [313:11] separated by a comma as you can see. So [313:14] that's the role of delimiter here. We [313:17] simply need to provide a list to the [313:20] join method. Then it will convert it [313:22] into a string. Right? And uh yeah, we [313:26] also have to tell the join how you want [313:28] to to separate your list elements. You [313:31] can specify anything. Maybe space which [313:34] is the default [313:36] comma maybe uh this hyphen. [313:42] This time the string will be separated [313:43] by hyphen as you can see. So that's it [313:46] for this video guys. In this video we [313:49] are going to learn about modules in [313:51] Python which are extremely important. A [313:54] module is simply a Python file that [313:57] contains code. This code can include [314:00] functions, classes or variables that can [314:03] be used in other programs. Once you [314:06] create a module, the code you place or [314:09] write in that file can be reused across [314:12] multiple programs. Now there are many [314:14] functions that are commonly needed in [314:17] different programs. So instead of [314:20] writing the same code in every program, [314:22] you can place those functions inside a [314:26] module and then import and use them [314:29] whenever needed. This allows you to [314:32] avoid repetition, saves time, improves [314:35] efficiency, and keeps your code clean [314:37] and well organized. So modules help you [314:40] organize your code into smaller [314:42] manageable pieces instead of writing [314:45] everything in one large file. There are [314:47] two types of modules in Python. Built-in [314:50] modules which come pre-installed with [314:53] Python and custom modules which are [314:56] created by the programmer. In this [314:59] particular video, we will focus on [315:00] built-in modules. A built-in module is a [315:03] module that comes pre-installed with [315:06] Python as part of the Python [315:08] installation, which means they are [315:10] already built, tested, and ready to use. [315:13] No additional installation is required. [315:16] For example, we have the math module. [315:18] Inside the math module, there are many [315:20] functions already written to solve [315:22] different mathematical problems. You [315:24] don't need to write these functions [315:27] yourself. You simply need to import the [315:29] module and use them. Now let's dive into [315:33] the practicals. Now first thing that we [315:35] need to do is import the module that we [315:38] want uh to use. To import we have the [315:43] keyword called import space. Now we need [315:46] to specify the [315:48] module name that you want to import. Uh [315:50] I'm going to start with uh the math [315:52] module. So math. So here I am telling [315:56] Python that import or include this math [315:59] module inside my program. Once a module [316:02] is imported or included then we can [316:05] access all the functions that a module [316:09] provides. Right? By default Python is [316:12] designed to be lightweight. Uh it only [316:15] loads the core modules. It doesn't [316:19] import the additional modules like math [316:22] OS and many more. We need to import [316:25] additional modules that we need manually [316:27] like this using the import keyword. Now [316:30] let's see how we can access the [316:32] functions that this math module offers. [316:37] Print. Now to access functionality of a [316:41] of a module write the exact module name [316:46] which is math for me. dot after dot we [316:50] can access uh the functions or variables [316:53] inside a module. Now uh in math module [316:56] there is a function called square root. [316:58] So s qrt this is the exact function name [317:03] parenthesis. Now uh provide it a value [317:06] let's say 16 square root is going to [317:09] calculate the the square root of the [317:12] provided number 16. Let's execute the [317:15] code. As you can see we have the [317:17] expected result right square root of 16 [317:20] is four. So that's how you access [317:23] function of a module. We write the exact [317:26] module name then dot after dot we can [317:29] access the function of a module. [317:32] Similarly we have a lot of functions in [317:38] in the math module. So print [317:41] math [317:43] uh the next function is uh let's say [317:45] power. So p o w now it needs two values [317:50] base and consonant 2 comma 2 ^ of let's [317:55] say 8. So it will give us uh 256. [318:01] As you can see this way guys you can [318:03] access all the functions that the math [318:06] module has to offer. Okay, syntax is [318:09] going to remain the same. We just need [318:11] to know the function uh name that we [318:15] want to access or use. So, math.p means [318:20] inside the math module there is a [318:23] function called P power which which [318:27] calculates the power of a number. So [318:29] here calculate calculating 2 raised to [318:32] the power of 8. Right? So let's go with [318:35] uh 32bit 2 22 raised 2 raised to the [318:39] power of 32 and it will give us uh over [318:43] 4 billion as you can see. And another [318:46] useful [318:48] function that the math module offers is [318:52] math dot [318:54] factorial [318:57] uh five factorial of let's calculate [319:00] factorial of five we have 120 right [319:04] that's the power of modules right it [319:06] offers us the problems that are already [319:09] solved right here in in the math module [319:12] I'm able to access all these uh [319:14] functions s without any problems. Right [319:17] now, without the math module, we would [319:20] have to solve or write all these [319:22] functions manually. But here with uh the [319:25] math module, I just need to access the [319:29] function name and uh then provide it uh [319:33] a value or values then yeah it gets it [319:36] gets us the desired result. That's the [319:38] power of modules. In the upcoming [319:40] videos, we will explore a lot of useful [319:43] modules that you are going to use on a [319:45] daily basis. So that's pretty much it [319:47] for this video guys. We are continuing [319:50] where we left off in the previous video. [319:52] We are going to explore the random [319:55] module in Python. The random module is [319:57] used to generate random numbers and it [320:00] is incredibly useful for a wide range of [320:03] tasks. For example, you can use it to [320:06] generate random numbers within a given [320:08] range. Create passwords for security [320:11] purposes. Shuffle items in a list. [320:14] Select random elements from a list ATC. [320:18] Now let's dive into the practicals and [320:20] import the random module. So type import [320:25] random. Make sure that the spelling is [320:28] correct. Random. [320:30] Now first thing that uh we are going to [320:32] do is generate a random number. So [320:36] random write the exact module name that [320:39] is random dot [320:42] rand int. [320:44] Now the random module provides a [320:47] function called rand int. It generates a [320:50] random number based on the range that [320:52] you specify uh to it. So we need to [320:56] provide a range let's say from 1 comma [321:00] 10. Now rand int is going to generate a [321:03] random number between 1 to 10. [321:08] As you can see every time you run the [321:11] program it returns a random value or it [321:14] generates a random value between the [321:18] provided range 1 and 10. 1 and 10 they [321:21] are also included. Okay let's increase [321:23] the range from 1 to 100. Now this time [321:26] it will generate a random number between [321:29] the provided range 1 to 100. [321:33] As you can see [321:36] we have a very similar function uh to [321:38] rain int [321:42] print [321:44] random dot [321:48] rand [321:50] range. [321:52] Uh it also needs a range 1 comma 10. [321:57] Let's execute the code. As you can see, [322:00] we have the expected output. However, [322:03] the rain range is a bit different from [322:06] the rain int. It does not include the [322:11] stop or ending value. What is the stop [322:14] stop or end value? Here it is 10. It [322:17] doesn't include the end values. So it [322:20] will generate the random number between [322:23] 1 to 9. Okay, that's the difference. The [322:27] rand int includes both starting and [322:30] ending value. So it can it can generate [322:32] any random number from 1 to 100. On the [322:36] other hand, the rand range function is [322:38] going to generate the random number from [322:41] 1 to 9. The ending value is not [322:45] included. That's the only difference. As [322:48] you can see 9, you will never see 10. [322:51] Let's increase the range of range range. [322:55] Now it will generate a random number [322:58] from 1 to 99. Sorry, like this. And of [323:03] course guys, you can also store the [323:06] random values being generated by these [323:09] functions in a variable as well. Let's [323:12] say rand equal to this. then we can [323:16] access the variable. [323:20] Now this time the rand int is going to [323:23] generate a random number then store that [323:25] value in rand variable and down here I [323:29] can print that rand variable [323:34] as you can see. [323:37] Now next function that we are going to [323:39] explore is called shuffle. the shuffle [323:42] function that random module provides it [323:45] shuffles uh a list. So first let's uh [323:50] create a list a and uh assign it some [323:54] values. [323:56] Now random dot shuffle s uf [324:03] l I hope I'm getting the spelling [324:04] correct. Now provide a list. Here I I [324:09] have the list A. So within parenthesis [324:11] provide a list name which is A. Let's [324:15] print the list A. [324:20] As you can notice guys, we have a [324:22] different list. Right? Now if you notice [324:26] in the list I have uh specified list [324:29] elements in this order 12 45 67 8C. But [324:33] at line number four, uh I have provided [324:36] the list A to the shuffle function. So [324:39] shuffle function basically randomizes [324:41] your list. It takes elements from a list [324:44] then randomizes them. So every time you [324:47] run uh your program, it will randomize [324:50] your list elements as you can see. [324:56] So that's the shuffle function. Now next [324:59] function that is extremely useful is [325:02] choice. Now the choice function selects [325:06] a a character from a provided string. [325:10] For example, let's say car characters [325:13] equal to let's provide it characters [325:17] including numbers lower case upper case [325:24] print [325:26] random [325:28] choice. Now we we have to provide the [325:31] choice v choice function either a string [325:35] like this or a variable that contains a [325:38] string values. So I'm going to provide [325:41] it [325:43] cares variable that is storing this uh [325:46] string. Now the way the choice uh works [325:49] is it selects a single character from a [325:53] given string. So here it will select a [325:56] single character from this string. That [325:59] character can be anything. It selects a [326:01] random character. As you can see four K, [326:05] right? [326:07] That's the [326:09] choice function. It is extremely useful. [326:12] We will be using it for generating [326:14] passwords, cryptography, it is. Now, [326:17] like I was saying, you can also provide [326:19] it a string instead of uh a variable. [326:23] So, let me copy this whole thing and put [326:25] it here. It will produce the same result [326:31] as you can see. [326:36] So that's it for this video guys. In [326:38] this video we will take a look at the [326:40] datetime module in Python. The daytime [326:43] module is used to work with both dates [326:46] and times together. It allows us to [326:48] perform a variety of useful operations [326:50] such as getting the current date and [326:53] time creating or comparing different [326:55] dates and formatting dates into more [326:58] readable strings. ATC. This module is [327:01] essential for handling any tasks that [327:02] involves tracking, displaying or [327:05] calculating time and date values in [327:08] Python programs. Now let's dive into the [327:10] practicals and import the datetime [327:14] module. So type import date time. The [327:18] daytime module is structured differently [327:21] from most other Python modules. Most [327:24] modules use standalone functions, but it [327:27] uses classes to organize its [327:29] functionality. This class-based design [327:33] groups date and time operations [327:35] together. [327:36] And you don't need to worry about it. We [327:38] just need an additional step to access [327:42] its functionalities. Okay. Write x or [327:46] create any variable name x equal to uh [327:49] we are going to use the daytime daytime [327:52] module. So write the exact module name [327:55] that is date time dot again date time [328:02] dot [328:03] now parenthesis. [328:06] Let's print the x. [328:09] Let's execute the code. As you can see [328:12] we have the current date and time. Let [328:14] me break this down. Now date time. This [328:17] is the module name. As you can see that [328:19] we have imported dot datetime. Inside [328:21] the datetime module there is a class [328:23] called datetime and dot now this is the [328:27] method of the datetime class. In classes [328:30] functions are basically called the [328:33] methods. Now the now method or function [328:37] returns the current date and time. It [328:41] fetches your current date and time from [328:43] your local system. Then I'm storing uh [328:47] those details in the x variable. Down [328:49] here I'm printing the variable x. Right? [328:51] Let's reexecute the code. As you can [328:54] see, it returns the date and time. Later [328:57] in the video, I'll I'll demonstrate how [328:59] to format this date and time. Obviously, [329:03] in most cases, we don't need all these [329:06] details, specifically these microsconds, [329:09] right? We don't need them at all. Right? [329:12] Now let's see how we can access [329:13] individual details such as year, month [329:17] or week. After now write dot year. Year [329:22] is basically an attribute. It returns [329:25] year. This time the x is going to store [329:27] the current year. And down here I'm [329:30] printing x. Right? So let's execute the [329:32] code. As you can see year is 2026. [329:37] Now let's access the month. month only. [329:41] Daytime [329:44] dot daytime dot now parenthesis dot [329:50] month. Mon month month attribute returns [329:52] the current month. [329:56] Month [329:58] and one we have one. One means the [330:01] January. [330:03] We can also access the current hour. So [330:07] write hour hour return the current hour [330:11] as you can see 6 hour 6 means it is [330:14] currently 6 a.m. [330:17] week. [330:19] Okay looks like there is no attribute [330:22] called week. We do have a attribute [330:25] called an attribute called day. It [330:27] returns the current day which is 26th of [330:29] January. We can even access [330:33] second [330:34] like this [330:37] as you can see. [330:39] And the simple now method returns the [330:42] current date, date and time like this. [330:44] Right? Now let's format this date and [330:47] time. Right? I want only these details [330:52] like this. I don't want seconds and [330:54] microsconds. Just these details. Now to [330:57] customize and display the date and time, [330:59] we have a method called string format [331:03] time. Okay, it allows us to customize [331:05] the date and time accordingly like the [331:08] way we want it. So what I'm going to do [331:11] is I'm going to pull the format codes [331:15] inside my program. [331:19] Now these are basically called the [331:21] format codes that allow us to highly [331:24] customize date and time formatting. They [331:27] are part of the string format time. [331:30] Okay, as you can see I have commented [331:33] them out. So let's see how we can use [331:36] them. Let me copy this date and time. [331:41] Now [331:42] after now dot like I was saying we have [331:45] string format time that allows us to [331:49] customize the date and time. So write [331:51] str f is for formatting. Now write time [331:57] parenthesis within parenthesis we can [331:59] use these string formatting codes. All [332:03] these codes represent a different value. [332:06] For example, modulus A, it represents [332:08] the full week day. For example, Thursday [332:12] or whatever the current day is. So [332:15] within quotes modulus A, let's execute [332:19] the code. As you can see, it is Monday. [332:22] I want to start with year. Here is [332:25] format code for year is this [332:31] percentage uppercase Y. It will print [332:33] the year. Now after here I want to print [332:37] month for month. The format code is uh [332:41] this B. So modulus B. [332:49] Now as you can see January 2026. Okay [332:51] let's swap these values. [332:59] January 26. [333:01] And of course I also need to print the [333:05] exact day. Format code for printing the [333:08] exact day is this modulus lowerase t [333:12] modulus lowerase [333:14] d [333:17] as you can see 26th January 2026. And I [333:21] also want the current time. Okay. So I'm [333:25] going to start with the hour. Of course [333:27] modulus H uppercase H for hour. [333:32] The current hour is 6th and then minutes [333:37] for minute we have the minute sorry [333:42] percentage and uppercase m. Let's [333:46] execute the code. As you can see this is [333:48] not looking like a time right? If they [333:50] are looking rather two different values [333:52] separated by a space. So between them [333:56] put a colon like this for a proper [334:00] formatting. As you can see 26th January [334:02] 2026 the current date and time. And of [334:06] course we can also you know format these [334:08] values. You can add hyphens between them [334:11] like this. As you can see 26th January [334:15] 2026 current date and date and time. So [334:18] guys these are the codes that as you can [334:20] see that you can use. You can use them [334:22] however you like or whatever order you [334:26] like. So guys, feel free to experiment [334:28] with these format codes and let me know [334:31] if you have any any questions. In the [334:34] previous videos, we worked with built-in [334:37] modules, right? These are builtin or [334:40] pre-built modules that are already part [334:43] of the Python. Now, we are going to [334:45] create our own modules. Creating your [334:48] own Python modules is straightforward. A [334:50] module is just a Python file that [334:53] contains functions, classes or variables [334:56] you want to reuse. Creating your own [334:58] module is actually quite simple. So [335:00] let's dive into the practicals and [335:03] create our own module. Okay. Now, first [335:06] thing that we need to do is create a [335:09] Python file. A Python module is nothing [335:12] just a Python file where we can you know [335:15] place our code then import that code in [335:18] our program. Right? So create a new [335:21] Python file. [335:23] New. Now we need to save the file in the [335:28] same directory where you have your main [335:31] file. Right? My main file where I'm [335:33] going to import the Python module [335:36] hello.py. It is in my Python directory. [335:38] So I will have to store uh my file or [335:42] module in the same directory as my main [335:44] file. Okay. So let's save it here. As [335:47] you can see this is the directory where [335:49] I have my main file. Here I'm going to [335:51] save this module. Okay. So let's say [335:56] pi module [335:58] dopy. Make sure to add the py extension. [336:02] It is extremely important because a [336:04] module is just a python file right that [336:07] contains the code. Now let's write some [336:09] code inside this uh file or module x = [336:15] 90. So here I have uh created a [336:18] variable. Now I can access this variable [336:21] inside my module. Okay. Now let's import [336:24] the module. Write import. Now write the [336:28] exact module name which is pi mod for me [336:33] pi m. And uh of course do not include [336:38] the py extension just the module name. [336:41] Now the import keyword is going to [336:44] search for this module in your uh [336:46] directory where your main file is where [336:49] you are importing this module in. Now [336:54] inside this uh pi mode module all I have [336:58] for now is this x variable. Now I can [337:01] access this variable. [337:04] Syntax is simple. Write the [337:07] module name that you have imported which [337:09] is pi mode dot x. As you can see x [337:14] variable is indeed present inside this [337:16] module. Let's execute the code. As you [337:19] can see we have successfully accessed [337:21] the x variable that is inside our module [337:24] pi mode. [337:29] Now we have a different value because we [337:31] changed the value inside this module. [337:34] Now let's create a few functions inside [337:37] this module. Let's create a function for [337:41] adding numbers. Now this function is [337:43] going to accept two arguments or values [337:46] a b. Then it will return [337:52] sum of a + b. Okay. So function name is [337:58] add. [338:01] So pi add let's provide it two [338:04] arguments. Let's execute the code. As [338:08] you can see we have the 79. So what [338:11] basically happening here I'm calling [338:13] this function that is inside this module [338:16] pi mod. As you can see I am passing [338:19] these two values 12 and 67. The first [338:22] value gets stored in the first parameter [338:25] a. Second value gets stored in the [338:27] second parameter b. Then here I'm [338:29] returning sum of a + b. Right? So return [338:34] function is going to return the sum of a [338:37] + b. Then here I'm printing the sum of a [338:42] + b. Right? This way guys you can create [338:47] as many functions as you like inside a [338:50] module. Let's create another function [338:52] called uh [338:54] multiplication and it is going to accept [338:57] two [338:59] arguments as well. [339:02] It will return a into b. Let's call [339:10] the function pi mod. This is the module [339:13] name and the function name is multi [339:20] Let's provide two values to it and we [339:25] have the expected result. So guys, this [339:27] way you can create as many functions, [339:29] variables or even classes in a Python [339:32] module. Then you can access those [339:34] functions or variables inside your main [339:38] file. We just need to import it like you [339:41] would import any other module, right? So [339:45] import then you can access variables or [339:48] whatever functions you have written [339:50] inside that module. So that's how guys [339:52] you can create your own modules. It is [339:55] very easy. Now creating modules is [339:58] extremely useful when you are working [340:00] with big projects where you have you [340:02] know tens of files right? Uh typically [340:05] in large programs there are certain [340:07] functions that you will be reusing a [340:10] lot. Okay. So in such cases what you can [340:14] do create a module write those functions [340:17] that you are going to need repeatedly [340:20] save them in a module then you can you [340:23] know reuse those functions like this [340:25] just import that module then you know [340:27] use those functions. So let me summarize [340:30] what we did in this video. To create a [340:33] module, we just need to create another [340:35] Python file with py extension and that [340:39] file must be saved in the same directory [340:42] where your main Python file is stored or [340:47] saved. Okay? Because when you import a [340:49] module, uh your program is going to [340:52] search for that file in the same [340:54] directory where uh your main file is [340:57] stored. That's the only thing that you [341:00] need to be careful about. We have [341:02] already learned that Python comes with [341:05] hundreds of built-in modules such as [341:08] math, math, OS, and many more. In [341:11] addition to built-in and user created [341:13] modules, Python allows us to download [341:15] and install external modules. These [341:18] external modules are developed by other [341:21] programmers and made available to [341:24] everyone. and they can be installed [341:26] easily using package managers such as [341:29] pip. These are known as thirdparty [341:31] modules or external libraries. They [341:34] allow us to add powerful features to our [341:37] programs without writing everything from [341:39] scratch. Python has thousands of [341:40] thirdparty modules available for almost [341:43] every domain including web development, [341:45] cyber security, data science, [341:47] automation, machine learning and more. [341:50] Python's ecosystem is huge and almost [341:53] any task or domain you can think of [341:56] already has a module available for it. [341:59] Now to install, upgrade and manage [342:01] external modules or libraries, we use a [342:04] specific tool provided by Python called [342:07] PIP. PIP is Python's package installer. [342:11] It allows you to install, upgrade, [342:13] remove, and manage external libraries [342:16] and modules that are not included with [342:19] Python by default. There are two [342:22] versions of pip. PIP and pip 3. PIP [342:25] traditionally was used to install [342:28] packages for Python version 2. It was [342:31] developed specifically for Python 2. [342:33] Since Python 2 has reached end of life [342:36] and is no longer supported and [342:39] maintained, this version of pip is no [342:41] longer relevant. Now, pip 3 is used to [342:44] install packages for Python 3 and later [342:47] versions. Python 3 is the current [342:49] version of Python. However, you will [342:52] still see many people using the pip [342:55] command to install packages for Python [342:58] 3. This is because on most modern [343:00] systems, pip is automatically linked to [343:03] pip 3 in the background. When you run [343:06] pip while using Python version 3, it [343:09] automatically executes pip 3 in the [343:11] background. As a result, in most cases, [343:14] both pip and pip 3 install packages for [343:17] Python 3. Even though pip 3 is is the [343:20] more explicit and recommended command. [343:23] Now, let's dive into the practicals. We [343:26] are going to start by checking the [343:29] installed modules or libraries external [343:32] libraries. So type pip. We have the [343:34] package manager called pip. So type pip [343:38] or pip 3 space and then type list. It is [343:42] going to list or display all the [343:45] installed packages. As you can see these [343:47] are the packages that I have installed. [343:49] And this list might be different for you [343:52] or you may not see anything at all here [343:54] because I have already installed these [343:58] uh packages. Right? So yeah, that's how [344:00] you can check all the installed [344:02] packages. Now let's see how we can [344:05] install a package. So open your web [344:09] browser and visit this website ppi.org. [344:15] This is the website where all the [344:17] external uh packages or modules are [344:20] hosted. This is basically a central [344:23] repository where you can find all the [344:25] packages. Now in the search box, type [344:27] the package that you are looking for. Uh [344:30] let me search for let's say requests [344:33] requests. Press enter. And here we have [344:36] all the matching results. Now I'm going [344:39] to click on the first match. As you can [344:41] see guys, here we have the installation [344:43] command at the top, right? And down here [344:46] you can find the documentation [344:49] authors. As you can see, these are the [344:51] authors of this module. And here that's [344:55] how you can use this this requests [344:57] module. As you can see, [345:02] now let's install uh this requests [345:05] module here. As you can see, command is [345:07] given at the top. You can click on it to [345:10] copy it. Click on it. Once it is copied, [345:13] back to the terminal or you can also [345:16] type manually. Now your question obvious [345:19] question might be which command should I [345:22] use pip or pip 3 [345:26] pip 3. So as we have already discussed [345:29] the if your python version is uh 3 point [345:32] and beyond then we need to use pip 3. So [345:36] let's check the Python version. [345:40] As you can see this is the my current [345:43] Python version. So if you are installing [345:46] a module for Python version 3 point and [345:49] beyond then we need to use pip 3 and pip [345:54] is exclusively used for Python 2 and [345:58] Python 2 is obviously no longer [346:00] maintained. It is old and outdated. [346:03] Nobody uses the Python 2. However, you [346:06] can use both pip 3 and pip to install. [346:11] Okay. So, let's install the requests. [346:13] So, type pip 3 install. [346:19] Now, write the package name that you [346:21] want to install. Make sure that uh you [346:24] type the correct package name because [346:27] the package name that you enter must be [346:29] available in the repository repository [346:32] of this pip py.org. Right? [346:38] So press enter. It will install the [346:41] package. As you can see it has been [346:43] installed. Now you can install the same [346:48] package with just simple pip command as [346:50] well because as we have already [346:52] discussed if you only use pip then [346:55] python in the background links to pip 3 [346:58] because when you use the simple pip [347:00] command in python 3 version python [347:03] automatically executes the pip 3 in the [347:07] background when you only type pip. So it [347:09] really doesn't matter what you use pip [347:11] or pip 3. But it is always recommended [347:13] to use uh pip 3 explicitly when [347:16] installing packages for the python [347:18] version 3 like this. [347:22] You can use of course just pip as well [347:24] because in many places you will see [347:27] people using pip. Okay. So in most cases [347:30] it really doesn't matter whether you use [347:32] pip or pip 3. So that's how you can [347:35] install a package in python. So before [347:38] installing any package, first thing that [347:40] you should always do is check for that [347:44] particular module here in the website. [347:46] Right? If that module is available here, [347:49] then it can be installed. If it is not [347:52] here, then you won't be able to install [347:54] that module with paper. Okay? Now let's [347:57] see how we can uninstall a package. So [348:00] first let's list all the packages. I [348:04] want to uninstall this requests package. [348:08] So command is simple. pip. You can write [348:12] pip or simply pip 3 like this. [348:15] Uninstall. [348:17] Uninstall. [348:19] Now specify the exact module that you [348:21] want to uninstall. [348:28] Press enter. Okay. [348:31] un noun command. Okay, sorry I there is [348:36] a spelling mistake here. Uninstall it is [348:39] now it should work just fine. Now found [348:43] requests would remove. Now here as you [348:46] can see it is it is waiting for my [348:48] confirmation if I want to uninstall it [348:51] or not. Press Y. Y is for yes. It will [348:54] uninstall the uh requested package which [348:57] is request sir. So guys that's it for [348:59] this video. That's how you can install [349:01] and uninstall packages. In this video, [349:03] we are going to take a look at the time [349:05] module. The time module is quite simple [349:08] and focuses manually on delays and [349:11] timestamps. It is somewhat similar to [349:13] daytime module, but daytime is more [349:16] advanced and powerful version designed [349:19] for working with real dates and times. [349:21] The time module is mostly used for for [349:26] pausing your program execution. It has a [349:28] function called delay which pauses your [349:31] program's execution. So if you want to [349:33] delay the execution of a program or [349:36] create something like a countdown, you [349:39] need the time module for that. So we are [349:43] going to start with a simple example, [349:44] then later we'll create a countdown. [349:47] Let's dive into the practicals. First we [349:50] need to import the time module. Now I'm [349:53] going to write two print statements. [349:56] Then add a delay between them. So print [350:02] hello. Let's use the time module. [350:05] Time dot sleep. Sleep is a function. [350:12] Inside the time module, sleep function [350:14] pauses the execution of a program. Now [350:18] within parenthesis, type let's say [350:20] three. So time dots sleep. So what [350:23] basically is going to happen after [350:25] executing line number three when Python [350:28] executes this time dots sleep with 3 [350:31] seconds it will pause your execution for [350:34] 3 seconds only after 3 second seconds [350:37] seconds it will execute the next line [350:40] which is this hello [350:44] world. So let's execute the code. As you [350:46] can see, hello. Then we have a delay and [350:49] after 4 seconds it printed. The next [350:53] print statement. Let's add the delay of [350:56] 6 seconds. This time after printing uh [350:59] this line at line number four, Python is [351:01] going to sleep for 6 seconds. Sleep for [351:06] 6 seconds simply means it will pause [351:09] your program's execution for 6 seconds. [351:12] only after 6 seconds it will execute the [351:15] lines of code that you have written [351:17] after the line number four. Let's [351:19] execute the code. As you can see hello [351:21] at line number three then we have a [351:23] delay here and now we have the hello [351:27] world. It was executed after the delay [351:30] of six seconds. That's how we can use [351:33] the sleep module. So whatever uh number [351:36] you put in within the parenthesis of [351:39] sleep, Python is going to pause the [351:42] execution for those many seconds. Now [351:45] let's pause the execution for a half [351:48] second. So 0.5. This time the delay is [351:52] only of half second. 0.5 as you can see. [351:57] Now let's create a countdown using the [352:02] sleep function. So let's create a loop. [352:06] So I = 10. Loop is going to start from [352:09] 10. It will keep running as long as the [352:12] value of I remains greater than equal to [352:16] 1. Let's print the variable I which is [352:21] this loops variable. Right? Now let's [352:24] increment the value of i by 1 and let's [352:28] implement the time dot sleep [352:33] and delay is going to be of 1 second. [352:36] Let's execute the code then I will break [352:38] down everything as you can see guys. Uh [352:41] okay this is not what I wanted. [352:47] Okay. Okay here [352:49] i minus one. [352:52] Now we should have a perfect countdown [352:54] starting from 10 to 1. [353:02] Okay, we have an error at line number [353:05] three. I = 10 [353:10] 10 9 8 [353:18] 2 1 and it ends here. So the loop starts [353:23] from 10 I equal to 10. So it will keep [353:25] running as long as the value of I [353:28] remains greater than and equal to 1. So [353:30] here I'm printing one. So when this loop [353:33] runs for the first time, the value of I [353:35] is 10. So here we are checking if the [353:38] current value of I which is 10 is [353:40] greater than and equal to 1. Condition [353:42] is true, right? 10 is greater than 1. So [353:45] block of loop gets executed. So here I'm [353:49] printing I. The current value of I is [353:51] 10. So it prints 10. Now we are [353:54] decrementing value of I by 1. I uh equal [353:59] to I minus 1. The current value of I is [354:02] 1. Sorry 10. So 10 - 1 becomes 9. Now [354:06] here Python executes this time dot [354:09] sleep. It pauses your program's [354:11] execution for 1 second. That's why you [354:14] know after printing each number there is [354:16] a delay of 1 second. Now after executing [354:19] this line control moves back to the y [354:22] loops uh control structure here. Now the [354:26] value of i is 9. Right? Now it checks if [354:29] 9 is greater than equal to one condition [354:32] is true. 9 is greater than 1. Right? So [354:35] it prints 9 here. The value of i gets [354:39] decremented by one again. it becomes 8. [354:42] 9 - 1 becomes 8. So it adds a delay of 1 [354:46] second. Right? Now control moves back to [354:48] the y loop again. Now this loop keeps [354:51] running until the value of i becomes [354:54] zero. Now when the value of i becomes [354:57] zero, python checks if uh 0 is greater [355:00] than equal to 1. Condition is false. 0 [355:02] is not neither equal to 1 or neither [355:05] greater than one. So as soon as [355:08] condition is evaluated to false the loop [355:11] exits right here loop is terminated [355:14] here. So we have this perfect counter. [355:16] So that's how guys you can use the sleep [355:19] function of the time module which is [355:20] extremely useful. In this section we [355:23] will be working with files also known as [355:26] file handling in most programming [355:28] languages including Python. File [355:31] handling is a core part of most [355:34] programming languages. It allows us to [355:37] create, read, write, and delete files. [355:40] This is incredibly useful because real [355:43] world programs often need to store data [355:46] permanently, read from existing files, [355:49] or manage files by creating or removing [355:52] them. In Python, file handling lets you [355:55] create new files, read data from [355:57] existing files, write or append data to [356:00] files, delete files when no longer [356:02] needed. This makes file handling [356:05] extremely valuable in real world [356:07] applications. In this uh particular [356:09] video, we will be reading contents of a [356:13] file. Now let's dive into the practicals [356:17] and read contents of a file. To read [356:20] contents of a file, first we need to [356:23] open that file. Once that file is [356:26] opened, then we can read its contents. [356:30] So type file equal to to open a file in [356:33] Python. We have the open function. So [356:35] open within parenthesis we need to [356:38] specify two things. We have to tell the [356:41] open function the file name or file path [356:44] that we want to open and its mode. Okay. [356:49] First let's uh specify the file name [356:51] that we want to open. Now I want to open [356:55] a file [356:57] here. As you can see in my current [356:58] working directory which is Python for [357:01] this session. Here I have this file [357:03] called demo.txt. I want to open it and [357:07] read its contents. So let me copy the [357:09] file name and put it here. [357:13] Comma. Now we need to specify the file [357:16] mode within quotes. Specify the file [357:19] mode. There are multiple file modes such [357:22] as read, write, append, ATC. Okay. Since [357:27] I want to read contents of this file, I [357:31] need to specify the read mode. So type [357:34] R. R stands for read. In read mode, we [357:38] can only read contents of a file. Okay. [357:42] The open function is going to check this [357:45] specified file demo.txt in my current [357:49] working directory. Here I have not [357:51] specified a full path rather only the [357:54] file name. So when you only specify the [357:57] file name, the open function will search [358:00] that file in your current working [358:03] directory. Then open it if that file [358:06] exists there. Now my current working [358:09] directory for this session is this. In [358:11] my current working directory, I do have [358:13] this demo.txt [358:15] file. So it will open this file. So if [358:18] you want to follow along then create a [358:22] text file in your current working [358:24] directory and put some contents in it [358:27] then specify that file name inside the [358:30] open function like this. Okay. And later [358:33] of course I will also demonstrate how to [358:36] read contents of a file that is located [358:40] in another directory or location. Now [358:44] the open function is going to open this [358:47] file in read mode then store those [358:50] details in the file variable. As you can [358:53] see open function doesn't actually read [358:56] contents of a file. It only opens that [359:00] file or it establishes a link to that [359:03] file. Once Python locates the file, it [359:06] establishes a link to it. Then store [359:09] those details in the file variable. It [359:12] is technically called the file object. [359:14] Let's actually print the file variable [359:16] and see what it is storing. [359:21] As you can see in the file variable, we [359:23] have these details. File name. This is [359:25] the file name that I want to open. Uh [359:28] the mode is read and this is the [359:32] encoding. Right [359:34] now using this file variable, we can [359:37] open this demo.txt file. Okay, this file [359:41] variable is holding the important [359:44] information that uh that is needed to [359:47] open a file. Now to actually read the [359:51] contents of a file, we have the read [359:54] function. So this file variable as you [359:57] can see now this is technically called [359:58] the file object. Using this file object, [360:01] we can perform operations such as [360:04] reading contents or writing contents to [360:07] it. Now let's actually read its content. [360:10] So specify the variable that is storing [360:13] your file uh details. For me it is file [360:17] then dot read [360:20] uh function actually reads the contents [360:23] of the specified file. Here I'm telling [360:25] Python that open this demo.txt file. [360:30] Once it is opened then we are reading [360:33] its content. [360:36] As you can see guys, we have [360:37] successfully read contents of this demo. [360:41] TXT file. Right now, by default, the [360:44] read function reads all the contents of [360:48] a specified file. As you can see, it has [360:51] read all the contents. Now, in most [360:55] cases, we do not directly print contents [360:59] uh of a file like this. What we have to [361:03] do is uh store the contents in a [361:07] variable like this [361:09] content equal to file dot read. Now the [361:12] read function is going to read contents [361:15] then store that content in the content [361:18] variable and let's print the content [361:20] variable [361:22] and re-execute the code. We have the [361:25] same exact output. Right now the content [361:28] variable is storing the contents of the [361:32] demo. TXT file. Now after performing the [361:37] desired operation on a file, we need to [361:40] close uh that file. Right here I have [361:44] performed the operation uh operation [361:47] which is reading contents of a file. Now [361:50] after reading its contents I need to [361:53] close this file which is extremely [361:55] important and recommended for a better [361:59] performance. So let's close the file. So [362:02] file dot close method is going to close [362:07] the file. Now what does it mean when we [362:09] close a file? It simply means it will [362:13] free the resources that this uh file is [362:17] consuming. Now see what happens is that [362:19] when you open a file and read its [362:22] contents your file takes or consumes [362:26] system resources such as RAM, CPU time, [362:29] ATC. Now if you open a large file then [362:32] it takes a lot of system memory or RAM. [362:36] That's why it is important to close. [362:39] Once you read uh the contents then we [362:42] need to close it. Once you close a file [362:45] then it will free those resources and [362:49] make them available for other processes. [362:52] So let's execute the code. As you can [362:56] see we have no visible uh difference or [363:00] output at all because nothing happened. [363:03] The close uh function closes the file in [363:07] the background. Once a file is closed, [363:09] you can't, you know, access its contents [363:11] or perform any operations such as uh [363:14] writing contents to it. Now let's see [363:17] how we can read contents of a file that [363:21] is stored uh in another directory. For [363:25] example, here I in my desktop I have [363:28] this dummy uh file, right? I want to [363:31] read its content. Now the only thing [363:35] that uh we need to do is specify the [363:39] full path to this file. We have to tell [363:42] the open function exactly where this [363:44] file is stored which is in desktop. So [363:47] type C c/ [363:51] Now instead of typing the path manually [363:54] let's copy the path which is the [363:57] recommended way. So click on the right [364:00] click on the file that you want to open. [364:03] Click on properties here. As you can see [364:06] this is the complete location or path. [364:08] Let's copy the path and put it here. [364:14] Now this is the directory where this uh [364:17] the file is stored. However, we have not [364:20] specified the file name yet. So forward [364:23] slash. Now specify the file name as [364:26] well. So file name is dummy [364:29] uh dummy sorry dummy. Now after the file [364:32] name we need to specify the extension as [364:35] well which is extremely important. Now [364:38] to find the exact extension again go to [364:41] the property [364:44] and uh the extension is txt. So [364:49] dummy.xt. So here I'm telling open [364:52] function that go in my desktop and [364:56] inside desktop I have this dummy.txt [364:58] file. Open it in read mode. Now it will [365:02] open this file and down here we are [365:06] printing its contents. Let's see if it [365:10] works or not. And we should have our [365:12] first error. As you can see we have the [365:15] syntax error. The exact error is this [365:18] uni code escape. Now what uh basically [365:21] is happening here? [365:24] Now the error is this backslash. What [365:27] basically is happening? If you remember [365:29] guys, [365:31] we use backslash to start a special [365:34] character or an escape sequence uh like [365:38] back slashn which creates a new line or [365:41] back slash t etc. right so here I have [365:44] provided this backslash. So when you [365:47] write a backslash uh inside a string [365:51] like this, Python assumes that you want [365:54] to write an escape sequence. So after [365:57] backslash, it expects you to write uh [366:00] something like n or t. So it is not [366:03] interpreting it as a path separator. [366:06] Rather, Python is assuming that you want [366:09] to start an escape sequencer. That's why [366:12] we have this error. So to fix this [366:15] error, it is simple. Just write R at the [366:19] beginning or before the double quote [366:21] like this. R stands for raw. Raw means [366:26] interpret this backslash as it is. Do [366:29] not interpret it as as a start of an [366:33] escape sequence. Okay. Now it should fix [366:36] the error. As you can see I I am a I am [366:40] reading contents of this dummy. txt file [366:42] which is located at uh this path. Okay. [366:47] So if you do not want Python to uh [366:50] interpret backslash as a start of an [366:53] escape sequence then write r it will [366:57] interpret or read it as as it is not a [367:01] start of an escape sequencer. Now there [367:04] are multiple ways to fix the same error. [367:07] Just remove the R. You can write two [367:11] backslashes like this. It will fix uh [367:15] the error as well. [367:18] Let's execute the script as you can see. [367:21] Or you can use uh [367:24] forward slash. [367:28] It will also fix the error. [367:33] Let's execute the code. As you can see [367:36] now the recommended [367:38] way uh to remove this error is this R. [367:42] Okay, just specify the R. Then you can [367:46] uh you can you know specify either [367:48] backslash or forward slash. It doesn't [367:50] really matter as you can see. [367:55] So this is the recommended uh method. [367:58] Use R and then you can use back slash or [368:01] forward slashes like this. So that's [368:05] pretty much it for this video guys. We [368:08] will continue from where we left off in [368:10] the previous video. In this video, we [368:12] will learn how to read a specific number [368:15] of characters from a file as well as how [368:18] to read multiple lines or any number of [368:20] lines you want. Now let's dive into the [368:23] practicals here. As you can see, I [368:25] already have the open function and I am [368:28] opening a demo.xt file in the read mode, [368:32] right? and then storing those details in [368:35] my file object or file variable. Right [368:39] now let's print uh the contents of the [368:43] demo.txt [368:45] file. So file dot read [368:50] function is going to read uh the [368:52] contents of demo.txt file and print [368:55] function is going to print that content. [368:57] Right? Let's execute the code and we [369:00] have the expected output. Right. The way [369:04] uh the read function works is by default [369:07] it reads all the contents of a file. [369:11] This is exactly what is happening here. [369:13] So read function has read all the [369:15] contents of this specified file. Now [369:18] let's say you want to read a certain [369:21] number of characters then we have to [369:24] provide that number uh within the read [369:28] functions parenthesis. So five this time [369:32] the read function is only going to read [369:35] the five characters from the beginning. [369:38] Okay, as you can see it has read the [369:41] exactly five characters. Let's make this [369:44] number 15. This time it will read 15 [369:48] characters. So whatever number you put [369:51] in here, the read function is going to [369:53] read that many characters from the [369:57] beginning. Let's go for let's say 77. [370:01] This time it should print 77 [370:04] characters. As you can see now we are [370:07] going to read contents of this file line [370:10] by line one line at a time. Uh now the [370:14] function for reading an entire line is [370:17] read line. [370:20] The way the read line function works is [370:23] it reads one line at a time. So let's [370:27] execute the code. As you can see guys, [370:29] it has read the first line. It obviously [370:32] starts from the first line. So read line [370:34] is going to read the first line from [370:37] this specified file. It reads the entire [370:41] line. Now what happens if you execute [370:44] the same read line function again? [370:48] This time as you can see we have two [370:51] lines. Okay. So when I executed the read [370:54] line function for the first time, it [370:56] read the first line and when I executed [370:59] it for the second time, then it [371:01] automatically moved to the next line and [371:05] read that line as well. Now if I execute [371:10] read uh two more times, then we should [371:12] have four lines. So as you execute the [371:15] read line function, it automatically [371:17] moves to the next line. Right? Now let's [371:20] say I want to read maybe first 100 [371:23] lines. Now if we keep going with this [371:27] method then we we need to write 100 read [371:31] line functions obviously which is not [371:34] efficient and scalable. What we can do [371:36] is obviously use the for loop. Okay. So [371:41] for i in [371:43] range uh let's say I want to actually uh [371:46] read seven line because in this file I [371:49] don't have 100 lines. I only have like [371:51] 10 or 12 lines. [371:54] So let's go for uh seven. Now this for [371:58] loop is going to run seven times. Okay. [372:01] Because loop is going to start from 0 to [372:03] 6. And in the block of this for loop, [372:07] write the read line function. [372:11] Okay. Okay. We have an error at line [372:13] number three [372:15] for i in uh range. Okay. I forgot uh the [372:19] obvious colon. Now it should fix the [372:22] error. Let's execute the code. As you [372:24] can see guys, it has read the exact [372:27] seven lines. Okay. 1 2 3 4 5 6. Okay. We [372:32] also have an empty line. empty lines [372:34] also get counted. Okay. So the way it is [372:38] working is when this loop ran for the [372:41] first time the read function was [372:43] executed. So it read the first line and [372:46] uh using printing print function we are [372:48] printing it. When this loop ran for the [372:51] second time the same read line function [372:54] was executed. So it read the second [372:56] line. On the third run this read line [372:59] function was executed third time. So it [373:02] read the third line. So read line [373:04] function keeps reading the lines as long [373:07] as this loop keeps running. So this loop [373:09] runs seven times. So it reads seven [373:12] lines and uh after that this loop gets [373:17] terminated. So after that it will not [373:20] read any more lines. Okay. So guys [373:23] that's how you can utilize this read [373:25] line function efficiently. And of course [373:28] I almost forgot close the [373:32] file. [373:34] So when uh the Python exits this for [373:36] loop here I am using the close function [373:39] which is going to close this file and [373:42] make uh the resources consumed by this [373:46] file available to other processes. As [373:48] you can see in this video we are going [373:50] to take a look at the with statement in [373:53] Python. As we have seen, it is important [373:55] to close files after performing [373:58] operations such as opening or reading [374:01] their contents or writing contents to [374:03] it. This is an important part of a [374:06] proper resource management. However, [374:08] manually calling close can lead to [374:11] problems if you forget to close the file [374:14] or an exception occurs before close is [374:18] executed among others. This is exactly [374:20] what the with statement solves [374:23] efficiently. The with statement in [374:25] Python simplifies resource management by [374:28] automatically handling system resources. [374:31] It is commonly used with files, network [374:34] connections and databases to ensure [374:37] resources are properly released even if [374:40] errors occur or you forgot to close. [374:42] That makes your code cleaner and more [374:45] readable. Now let's dive into the [374:47] practicals. So write with and let me [374:51] comment uh this line out [374:54] and uh let me copy the open function [374:58] with parameters [375:01] as file. Now guys this line is equal to [375:06] this exact same line right these two [375:09] lines are doing the same thing. So here [375:12] I am opening this uh demo.txt txt file [375:15] in the read mode then storing the those [375:18] details in the file object or file [375:20] variable. Now I'm doing the same thing [375:23] here with the context manager with it is [375:27] going to open this demo.txt file then as [375:30] keyword it is going to store those [375:32] details in the file variable. Now colon [375:36] within the block of uh this uh with [375:39] statement we can read the contents of [375:43] the file. So file as you can see here [375:46] file dot uh read [375:50] let's execute the code as you can see we [375:52] have the expected output we have [375:54] successfully read the contents of this [375:57] file okay so yeah this is the with uh [376:00] statement okay it handles the system [376:03] resources efficiently now with the [376:06] context manager with we do not need to [376:09] close the file manually the way we have [376:12] been doing so far Right? Like this pi [376:16] file dot close. Right? It is not [376:20] required because by default the width [376:23] statement is automatically going to [376:25] close the file. So how it is basically [376:27] going to uh going to work is here at [376:30] line number four we are reading the [376:32] contents of the file. After this we do [376:35] not have any lines of uh code. So after [376:38] the last line, it automatically closes [376:40] the file automatically in the [376:43] background. Now with the context [376:45] manager, it looks much more cleaner, [376:48] right? The code is much more organized. [376:51] We have to write everything within the [376:53] block of the with statement and it also [376:57] automatically [376:59] closes the file after the last line [377:02] within the block of width. Now the close [377:05] function is not required. Okay, you [377:07] don't need to write it uh manually with [377:10] the with statement. It does [377:13] automatically this for us. Okay, so [377:15] guys, that's how this with statement or [377:18] context manager works. In the previous [377:20] video, we read the content from if file [377:24] line by line using the read line [377:26] function, right? The obvious shortcoming [377:29] of the read line function is that we [377:31] can't directly access a specific line, [377:34] nor can we easily read all contents at [377:38] once or read a specific range of lines. [377:41] The read lines function addresses these [377:44] issues effectively. The read lines [377:46] function can read the entire file [377:50] content and store each line as a [377:52] separate element inside a list. Once the [377:56] lines are in a list, we can easily loop [378:00] through that list to process each line [378:02] one by one. The method is useful when we [378:05] want to quickly load all lines and then [378:09] work with them through a loop instead of [378:12] calling read line repeatedly. Now let's [378:14] dive into the practicals. Here I have [378:17] already opened this demo.txt file in uh [378:20] the read mode. Right? So uh let's first [378:24] read uh the contents of this file using [378:27] the read [378:30] uh method. Let's execute the code. As [378:33] you can see the way the read function [378:35] works is it reads all the contents of a [378:39] file as a single joint string. Now we [378:44] have uh another function called the read [378:48] lines. Now read lines function is [378:51] similar to read function but it returns [378:55] the content as a list where each line is [379:00] stored as a separate list element. So [379:03] let's execute the code. [379:06] As you can see here read lines function [379:08] has returned the content of this file as [379:12] a list. As you can see at the beginning [379:14] we have the square bracket. Square [379:16] brackets are obviously used to define a [379:19] list. Right? In this list, as you can [379:21] see, we have contents of this demo. .txt [379:25] file. The way it works is each line is [379:29] stored as a separate list element. As [379:34] this is the first line as you can see [379:35] this is the first line here. This is the [379:38] this first line is stored as a separate [379:41] list element or list item. Now this is [379:45] the second line and we have comma after [379:48] comma we have the second line. Now [379:52] before we proceed further as you can see [379:54] we have something unusual at the end of [379:57] each line we have this uh back slashn [380:01] which is the escape sequence for a new [380:04] line. As you can see after each line you [380:06] will see this back slashn or new line [380:09] character. Here we need to understand [380:12] how files store text lines. Files use [380:16] new line characters uh which is back [380:19] slashn to mark the end of each line. [380:23] When you are using a text editor and [380:25] press enter, your text editor does two [380:29] things. It moves your cursor to the [380:32] beginning of the next line and [380:35] internally it also inserts a back slashn [380:39] or new line character at the end of the [380:42] current line automatically. Now when a [380:45] text editor or a program reads file [380:48] content the back slash n character is [380:51] treated or interpreted differently than [380:54] standard characters. It is not displayed [380:57] or printed as the literal character back [381:00] slashn. Rather, it is interpreted and [381:03] executed as a control instruction. Okay. [381:06] When a text editor or program encounters [381:09] back slashn, it immediately moves the [381:12] cursor to the beginning of the next [381:15] line. Now the Python's read line [381:18] function is designed to read contents of [381:21] a file exactly as it is stored on the [381:24] disk. This includes the hidden escape [381:27] sequence like back slash n. Now since [381:31] the read line function returns contents [381:33] of a file as a list. Now we can access [381:36] uh the individual list items using [381:39] indexes. Uh so first let's store uh the [381:44] contents that read lines function reads [381:47] in a variable. Let's say lines. [381:52] Uh let's print uh [381:55] lines. So here I'm reading contents of [381:59] the demo.xt file using read lines [382:01] function. Then storing that in the lines [382:05] variable. Right now lines is a list. As [382:09] you can see this is a list right? Read [382:12] lines as we already know the read line [382:14] lines function reads contents then [382:16] returns it as a list then we are storing [382:19] that in the lines variable. Now let's [382:22] say I want to access only the first line [382:25] then type zero the first element. This [382:29] is the first element of this array uh [382:32] sorry this list. So we should print the [382:35] first line as you can see. [382:38] Let's print uh [382:42] line number two. [382:46] As you can see, we have successfully [382:49] printed the first two lines. [382:54] Now, [382:56] let's loop through uh through this lines [383:00] list. So, for i in [383:03] lines. So, I'm basically looping through [383:05] this lines list. I want to print all the [383:09] lines one by one. So print [383:12] I. [383:13] As you can see guys, we have looped [383:16] through all the lines that are stored in [383:19] this file. Right now we also have these [383:22] unnecessary empty lines. I will get back [383:25] to this in a minute. So first let me [383:28] walk you through what is happening here. [383:29] So using read lines function we are [383:31] reading contents of this file. It [383:34] returns the contents as a list and we [383:36] are storing that in the lines variable. [383:38] Then we are looping through this lines [383:41] list one by one. Now here we have an [383:45] obvious problem right? We have all these [383:47] unnecessary empty lines. If I check the [383:50] contents of uh [383:53] uh this file that I have opened using [383:56] read lines which is demo txt. As you can [384:00] see uh in inside uh this this file I do [384:05] not have any unnecessary empty lines [384:08] right let's analyze how this read line [384:12] lines function reads the contents as you [384:14] can see read line function reads [384:17] contents like this right it returns a [384:20] list and at the end of each list item we [384:24] have this back slashn right back slashn [384:27] is a new line character error. So when [384:30] this print function reads this entire [384:33] line, it prints this line and it also [384:37] executes this escape sequence which [384:40] creates a new line. Now by default the [384:44] print function automatically adds this [384:48] escape sequence back slashn at the end [384:51] of each line. Now here the print [384:54] function executes the back slashn two [384:57] times. Okay, the first back slashn gets [385:00] executed because it is part of this [385:02] line. Right at the end we have back [385:05] slashn and the second back slashn [385:08] is automatically added by the print [385:11] function. That's why we have an [385:13] additional empty line. Now to get rid of [385:17] this we simply need to use end parameter [385:21] of the print function. In print function [385:24] we have a parameter called end. So end [385:27] equal to nothing or empty. So what [385:30] basically end does it overrides or [385:33] prevents the default behavior of the [385:36] print function. The default behavior of [385:38] the print function is that at the end of [385:41] each line, it inserts the hyphen n to [385:45] create a new line. So when you specify [385:48] the end parameter equal to nothing, it [385:51] will not add this back slash n escape [385:54] sequence at the end of each line. So it [385:58] will not create an empty line. So let's [386:01] execute the code and it should fix the [386:03] problem. As you can see, it has fixed [386:05] the problem. Now we still have uh you [386:08] know contents being printed line by [386:10] line. This is because that new line is [386:13] created by the backslash n that we are [386:17] reading from uh these array elements. So [386:21] when Python reads this line, it prints [386:24] this line and then we have escape [386:27] sequence then this escape sequence [386:29] backslash and it creates a new line. [386:33] Right? Now let's uh print a specific [386:36] number of lines. Let's say I want to [386:38] print first three lines. Then it is [386:41] simple. Here we can provide a range from [386:45] zero. Zero is the first element from [386:48] three. So it will print first three [386:52] lines. Let's execute the code. As you [386:54] can see guys, this time we are slicing [386:57] this array. I think we did the slice [386:59] array slicing in the arrays section. [387:02] Right? So zero means the index is going [387:04] to start from one. Then we are providing [387:07] three. Now the number that you provide [387:09] does not get included. Rather whatever [387:12] number you provide here that number gets [387:15] subtracted by one. So range is starting [387:18] from zero and ends at 3 minus 1 which is [387:22] two. So 0 is the first index. Second [387:25] index is 1. Third index is two. Right? [387:29] This way you can print lines in any [387:31] range. Maybe let's say from 3 to [387:35] 6. [387:38] As you can see, we have we have printed [387:41] lines from 3 to six. Now let's close the [387:45] file. file dot close. [387:51] Now it is always recommended to close a [387:54] file once you have performed the desired [387:57] operation. [387:58] In this section, we will explore error [388:01] handling in Python using try, accept and [388:04] finally blocks. Handling errors properly [388:07] is one of the most essential skills in [388:10] any programming language. Before we dive [388:12] into practical error handling, we need [388:14] to understand the type of errors in [388:17] Python. This will set the context for [388:19] learning how error handling works. There [388:22] are two main types of errors. Syntax [388:25] errors and runtime errors. Syntax errors [388:29] occur when there is a mistake in the [388:32] structure or syntax of the code such as [388:34] missing quotation mark or missing colon [388:38] maybe missing closing parenthesis ATC. [388:41] Now these errors are detected by Python [388:43] during parsing before the code is [388:46] executed. Now the code parsing in [388:49] programming means the process where a [388:52] language interprets, reads and analyzes [388:54] your code line by line to understand its [388:57] structure and syntax before execution. [389:00] Before your code is executed, Python [389:02] parses it to make sure that your code is [389:05] written correctly. During parsing phase, [389:07] Python detects syntax errors along with [389:10] other structural issues. Once Python [389:13] successfully parses the code without any [389:15] syntax errors, it begins executing the [389:19] program. During this execution phase, [389:21] certain errors may emerge that could be [389:24] detected only when the code is actually [389:28] running. These are known as the runtime [389:30] errors or exceptions. For example, if [389:33] you try to divide a number by 0 using an [389:37] expression like 23 divided by 0, it [389:40] won't cause a syntax error during [389:43] parsing phase because there is nothing [389:45] wrong syntactically. However, when [389:47] Python tries to execute it or divide it [389:50] by zero, it throws or raises a runtime [389:53] error because division by zero is not [389:56] allowed. Another example is working with [389:58] files. If you provide a file path that [390:01] doesn't exist, Python will raise an [390:04] error when it tries to access the file [390:07] during execution. Such runtime errors [390:10] can be a big problem because when Python [390:13] detects a runtime error, it immediately [390:16] stops code execution. Your program [390:19] crashes or stops right there. To catch [390:21] and handle runtime errors, Python [390:24] provides a feature called error [390:26] handling. Error handling is used to deal [390:29] with runtime errors using try and accept [390:33] blocks. These blocks allow your program [390:35] to catch and handle errors gracefully so [390:38] it can continue running without crashing [390:41] or stopping. Using try and block we can [390:44] easily catch runtime errors and allow [390:46] the code to continue running without [390:49] halting. Okay, I'll demonstrate it [390:52] practically in the next video. We are [390:54] going to continue from where we left off [390:57] in the previous video. In this video, I [390:59] will demonstrate how to catch and handle [391:01] runtime errors efficiently with [391:04] practicals. Now, let's dive into the [391:06] practicals. Before explaining the try [391:10] and accept blocks, I'm going to I'm [391:13] going to demonstrate how Python handles [391:16] the runtime errors. This will set a good [391:19] context for learning the try and accept [391:22] blocks or exception handling. So what [391:25] I'm going to do is I'll try to divide a [391:27] number by 0. 12 divided by 0. Now the [391:31] way Python execution works is before [391:34] actually executing the code, Python does [391:37] something called the code parsing. In [391:40] the parsing phase, Python checks for the [391:43] syntax errors. syntax errors like uh [391:46] maybe you have closing parenthesis [391:49] missing like this. Let's execute the [391:51] code. As you can see, this is called the [391:52] syntax error. The opening parenthesis [391:55] was never closed or maybe maybe you have [391:59] an unnecessary [392:01] code in your code, it is also a syntax [392:05] error as you can see. So this is what [392:06] Python does in the parsing phase. It [392:08] detects these syntax errors. However, if [392:12] you check uh this piece of code 12 [392:16] divided by 0, it will not generate any [392:19] syntax error because when Python parses [392:23] this uh this code, it sees that okay, [392:26] here I'm trying to divide these two [392:29] numbers, right? So, it will pass the [392:32] parsing phase. Here I'm simply trying to [392:34] divide uh two numbers. Python doesn't [392:37] detect these runtime or logical errors [392:40] in the parsing phase. However, when [392:42] Python actually executes this code [392:45] there, it will generate an error when [392:47] Python will try to divide 12 by 0 which [392:50] is not possible. So, it will throw an [392:54] error. That error is called the runtime [392:56] error because uh the error is caught uh [392:59] during execution or runtime. The major [393:02] drawback of uh of runtime errors is that [393:06] uh it crashes and terminates your [393:09] program. For example, let me write a [393:11] print statement. Hello. [393:15] As you can see, the line error was [393:17] caught at line number one. So, as soon [393:19] as this runtime error was uh detected, [393:23] the program stopped right there. It [393:26] crashed right there. all the lines of [393:28] codes written after it will not be [393:31] executed. Now to handle the runtime [393:34] errors efficiently, we have something [393:37] called exception handling or try and [393:39] accept blocks where we can uh we can [393:43] catch these errors and continue the uh [393:46] rest of the codes execution. So write [393:49] the try keyword try colon press enter. [393:53] In the try block, we need to write the [393:56] code that we want to implement. Let's [393:58] say 12 divided by 0. Now in the accept [394:03] block, outside of the try block, write [394:05] except colon. Make sure that there is [394:09] indentation in both try and accept [394:12] blocks like this. Print. Let's catch the [394:16] error. Can't [394:18] divide by zero. So the way try and [394:24] accept uh blocks work, they work [394:26] together. In the try block, we write the [394:28] code that we want to implement. And if [394:32] Python catches any runtime error in the [394:35] code that you write in the try block, [394:38] then that runtime error is passed to the [394:42] accept block. In the accept block, we [394:44] handle that error. So let's execute the [394:47] code. As you can see, can't divide by [394:50] zero. So in the try block we tried to [394:54] perform 12 divided by 0 which generated [394:57] a runtime error that error was passed to [395:00] the accept block. In the accept block we [395:03] are handling that error. So that's how [395:05] try and accept blocks work. In the try [395:08] block, we write some code and if the [395:11] code that you write uh within the try [395:14] block generates a runtime error, that [395:17] error is passed to the accept block [395:20] where we handle that error and it will [395:23] avoid the program crashing. For example, [395:27] the execution [395:30] continues. [395:34] Let's execute the code. As you can see, [395:37] we successfully caught the runtime error [395:41] here in the accept block. Then we have [395:44] this print statement outside of these [395:46] two blocks. So, Python executed this [395:50] print statement. So, it did not uh crash [395:53] or terminated the program after handling [395:56] the error. Rest of the execution was not [395:59] disrupted. Everything was executed as it [396:03] should be. So that's that's why the [396:06] exception handling is extremely [396:08] important. Now to simplify catching [396:11] runtime error handling, we can use the [396:14] built-in exception types that Python [396:17] provides. In the exception definition, [396:19] we can specify the type of error we want [396:22] to catch. This allows for targeted error [396:25] handling. For example, division by zero. [396:32] As you can see division by zero it [396:34] generates this particular error zero [396:37] division error. Now we can catch this [396:40] specific error by specifying this error [396:44] in the accept block. Okay. So copy this [396:47] uh error as it is now [396:53] except space paste it here as e. So this [396:58] time I'm telling Python that catch this [397:02] specific error only zero division error [397:06] right. So if in the try block Python [397:09] catches a zero division error then this [397:12] accept block will catch that particular [397:15] error zero division error and the error [397:18] message will be stored in the E [397:20] variable. As you can see as E in the E [397:22] variable the error message will be [397:24] stored. So this time we are handling it [397:26] automatically. Let's execute the code. [397:29] As you can see, division by zero. So [397:31] here in the try block, Python detected [397:33] the division by zero error. And in the [397:37] accept block, we are specifically [397:39] catching uh the division by zero error [397:41] by specifying the built-in zero division [397:45] error. So it catches that error. The [397:48] generated error message is stored in the [397:50] E variable. Then down here we are [397:52] printing that variable, right? The [397:56] variable as you can see it is storing [397:57] this particular error division by zero. [398:01] Similarly just like zero division error [398:04] error exception handling provides [398:07] different options and exception types [398:09] for catching various kinds of runtime [398:12] errors. We will explore them as we [398:14] progress in this course. Now we can also [398:17] use ex else with try and accept. So else [398:24] print no error was detected. [398:30] No runtime [398:33] error was detected. Let's execute the [398:35] code. Now as you can see the else block [398:38] is only executed when uh the try block [398:42] does not detect or catch any runtime [398:46] error. So let's divide [398:50] 12 by 2. As you can see this time we [398:53] have six because it is a valid [398:56] expression right 12 divided by two is [398:59] six. So no runtime error was detected. [399:02] So when uh the try block doesn't catch [399:05] any runtime error the else block gets [399:08] executed. But if I [399:11] divide 12 by 0 [399:14] then the accept block gets executed. [399:18] Here we are printing the error message [399:20] and catching the error. The else block [399:23] was not executed. So it is only executed [399:25] when Python doesn't catch any errors in [399:28] the try block. So that's it for this [399:31] video guys. In this video, we will take [399:34] a look at the finally block which is [399:36] also part of try and accept. The finally [399:41] block is an optional part of the try [399:43] except structure in Python. The finally [399:46] is a special block that always runs no [399:49] matter what happens in the try or accept [399:52] blocks. Now let's dive into the [399:54] practicals. [399:57] So uh let me write try block [400:01] print [400:06] except [400:12] can't divide [400:15] by [400:16] zero sorry zero right [400:21] so if I execute the code we are catching [400:24] uh the division by zero errors error [400:27] right so in the try block we write the [400:30] code if it raises a runtime error then [400:34] the accept block gets executed that's [400:36] how it works if there is no runtime [400:39] error in the try block then yeah except [400:42] block is not executed we also have [400:45] finally so write finally outside of [400:48] blocks of try and accept like this [400:52] print [400:55] code [400:56] continues. [400:59] Now the way finally works is it will be [401:02] executed whether there is a runtime [401:05] error or not. Okay, for example, [401:10] as you can see here in the try block, [401:13] Python did not catch any runtime error, [401:17] right? 12 divided by 2. So we have the [401:20] result and the finally block was [401:23] executed code continues. However, if I [401:26] try to divide by it by zero [401:31] as you can see can't divide by zero this [401:33] time since Python raised or detected a [401:37] runtime error. The accept block was [401:40] executed but finally block was also [401:43] executed. Okay. So finally block is [401:46] executed whether Python detects a [401:48] runtime error or not. The finally block [401:52] is always executed. The else as we [401:55] learned in the previous video the else [401:59] block gets executed [402:04] when there is no runtime error. Right? [402:08] So here as you can see here Python did [402:10] raise a runtime error. So block of else [402:13] was not executed. But if I divide 12 by [402:18] two, it will not raise a runtime error. [402:21] As you can see the block of else was [402:23] executed. So else when it is used with [402:25] try and accept, it is executed only when [402:30] Python doesn't detect any runtime error. [402:34] However, finally block is always [402:37] executed whether Python detects or [402:39] doesn't detect the runtime error. So [402:42] that's the finally block. It is [402:44] optional. [402:52] As you can see the binary block is [402:55] executed even though Python did not [402:58] raise any runtime error. And if Python [403:01] does raise a runtime error, it will [403:04] still be executed. So that's how the [403:06] finally block works. So that's it for [403:08] this video. In this quick video, I'll [403:11] demonstrate the use of exception [403:14] handling with real world examples. This [403:17] way you will uh get an idea of how [403:20] important the exception handling is. So [403:23] what I'm going to do is uh I'll ask user [403:26] to enter two numbers. Okay. Then try to [403:29] divide them. So a equal to intput [403:36] enter first number [403:42] second number. [403:46] So let's say you are creating a [403:47] calculator app right where you are [403:50] allowing users to to enter numbers. And [403:54] uh of course we don't know what users [403:56] can enter. So here let me [404:01] try to divide a divided by b. Sorry let [404:05] me replace a with b. So this small [404:09] calculator application let me execute [404:12] it. As you can see it is allowing user [404:14] to enter two numbers. Okay. And uh the [404:18] program is going to perform division. [404:20] Okay. Let's say user enters 56 then [404:24] second number is zero. As you can see [404:28] division by zero because we can't trust [404:30] users right what what they will enter we [404:33] have to prepare our program for every [404:36] possibility right they can enter [404:38] anything like like zeros so if your [404:40] program doesn't handle these errors then [404:43] yeah your code does look very [404:45] unprofessional and ugly. So it is [404:48] important to handle these runtime [404:50] errors. And of course we can uh handle [404:54] these errors with try and accept block [405:00] except [405:02] let me copy this specific error that I'm [405:05] going to catch [405:08] as E. [405:12] Print [405:14] E. [405:17] Now let's execute the code. As you can [405:19] see now we are handling this error [405:22] gracefully. So that's the use of the [405:25] exception handling. We can't trust the [405:28] user inputs. We we have to prepare for [405:31] every possibility, right? So our program [405:34] can work smoothly. So that's it for this [405:36] video. In this video we will learn how [405:38] to create files, write contents to them [405:42] and much more. This is going to be an [405:44] important video. Now let's dive into the [405:47] practicals and uh write contents to a [405:50] file. File equal to open. Uh let's [405:54] specify a file name. Let's say [405:56] dummy12.txt, [406:00] W. This time the file mode is W. W [406:02] stands for write. It allows us to write [406:05] contents to a file. As you can see in my [406:09] current working directory, I don't have [406:12] term12. [406:14] TXT file. So the way uh the right mode [406:17] works is the file name that you specify [406:20] here if it doesn't exist then it will [406:24] create that file. Okay. So let's execute [406:27] the code. Uh first let me save the code. [406:30] As you can see this file doesn't ex is [406:32] not here in my current working [406:34] directory. [406:36] ls as you can see the dum12.txt [406:40] has been created. Now let's write [406:44] contents to it. [406:46] File dot write. Now we have the write [406:50] method. The write method is used to [406:53] write contents uh to a file. Now we have [406:56] to tell the write function the file name [406:59] where you want to write the content to. [407:03] So here I am providing file dot write. [407:07] So write function is going to write [407:09] contents to the file dum12. txt right [407:13] because this file object or file [407:15] variable is storing these details [407:18] including the file name where the [407:20] content will be added. So within quotes [407:23] let's write content let's say a new line [407:28] added let's execute the code and we [407:32] don't have any output or errors we don't [407:34] have output obviously because we are not [407:37] printing anything let's ls now let's [407:40] open contents of this file in notepad [407:47] as you can see guys a new line added [407:49] this is exactly what we added to this [407:52] dum12.txt [407:54] file. Right? So that's how you can uh [407:57] you can add content or a line to a file [408:00] using the write function. Now we need to [408:05] close the file which is very very [408:07] important. [408:09] Now closing especially when writing [408:12] contents to a file is important because [408:14] if you keep the file open then processes [408:18] within your program might add data to [408:20] your file which which will cause the [408:24] problems and obviously it will consume [408:26] your system resources as well. So it is [408:28] important to close the file. Now the [408:31] write function allows us to add only one [408:35] line at a time. Now if you want to add [408:38] multiple lines then we have to use write [408:41] lines function like this. Now we need to [408:45] specify the lines within a list. Okay. [408:48] So within write functions parenthesis [408:51] write uh square brackets which are used [408:54] to define a list. Now specify the lines [408:57] that you want to uh append line number [409:00] one. [409:04] Now we need to specify the new line [409:07] character or escape sequence. If you [409:10] don't then all the lines will be written [409:13] uh as a single string or in a single [409:16] line comma [409:20] line to [409:29] comma [409:34] line number three. This way you can uh [409:38] include as many lines as you like. [409:42] Line number [409:44] four, escape sequence or new line [409:48] character. Make sure that the lines or [409:52] list items are separated by a comma. [409:55] This is mandatory. Let's execute the [409:57] code. So this time the write line lines [410:00] function is going to add these four [410:02] lines to this dum12.txt txt file. Okay. [410:07] Okay. We have an error. Unexpected [410:09] character line continuation character at [410:12] line number three. 1 2 3. We have comma [410:16] placed properly here. Okay. Okay guys, I [410:20] see I see where the error is here. I [410:22] have closed this string inappropriately. [410:25] So remove this and string must be closed [410:28] here after the back uh backslash and new [410:31] character. Now I think this should fix [410:33] the error. Okay, we don't have any [410:37] errors. Uh let's uh open uh the file. [410:43] As you can see guys, this time we have [410:45] successfully added these four lines to [410:49] this file. This way you can add as many [410:52] lines as you like to a file like this. [410:55] Okay. Now important thing that you [410:57] should understand is this new line [411:00] character. If you don't specify the new [411:02] line character or back slashn at the end [411:05] of each line, then all these lines will [411:07] be stacked like this. [411:11] So back slashn basically creates a new [411:14] line. That's why we have lines [411:16] separately in new lines. Right? Now as [411:20] we discussed in the previous video, it [411:22] is recommended to use the context [411:24] manager width. So here what I'm going to [411:27] do is uh write with [411:32] open [411:34] as file and [411:38] put these lines within the block of [411:41] width. So here I'm using the context [411:44] manager opening this file as file. Now [411:47] we have the file variable or file object [411:49] and here I am writing these lines to [411:54] this dumb one dot txt file down here and [411:59] now down here I don't need the file dot [412:01] close function because the context [412:04] manager with is automatically going to [412:07] close the file after the last line [412:10] because after line number five I don't [412:12] have any more lines so it will [412:14] automatically close the file. Let's [412:16] execute the code. [412:20] As you can see, we don't have any [412:22] errors. It means the code is working [412:24] perfectly, right? And before signing [412:27] off, you can create a file at any [412:31] location. Right? If you don't specify a [412:34] path here, then by default, the open [412:37] function is going to create file in your [412:39] current working directory. But if you [412:41] want to create a file at a specific [412:44] location, then you can uh specify path [412:47] to that directory. Let me actually show [412:49] it to you. Let's say I want to create uh [412:52] create a file in my desktop. So what you [412:54] are going to do? Go to the directory [412:56] where you want to create the file. I'm [412:58] in my desktop. So right click in empty [413:00] space. Click on open in terminal. I just [413:04] want to grab the current working [413:06] directory. [413:07] pwd. This is the complete path. and [413:10] let's copy it [413:14] and put it here [413:17] back slash let's create a file called [413:21] d123txt [413:24] and of course we have to add r at the [413:27] beginning to to interpret the path [413:30] separator backslash as it is not as a [413:33] start of an escape sequence this time [413:37] this d 1 2 3 5 1 to do txt file will be [413:41] created in a desktop. Let's execute the [413:44] code. As you can see, we don't have any [413:47] error. Let's go to my desktop. [413:50] And here we have the file D12. Right? [413:54] Let's uh open the file. In this file, we [413:56] have the we have these four lines. These [413:59] are the exact lines that I have written [414:01] to this file here. Right? In this video, [414:04] we are going to explore the OS module in [414:07] Python. It is one of the most important [414:09] modules that every programmer should [414:11] know about. The OS module uh is your [414:15] go-to toolkit for interacting with [414:18] operating system. It allows us to manage [414:20] files, folders, and process information [414:24] regardless of whether you are on [414:26] Windows, Mac OS, or Linux. It is a [414:29] built-in library that provides a way to [414:33] interact with the operating system. It [414:35] allows us to perform tasks such as [414:39] creating and deleting directories, [414:41] reading and writing files, checking [414:44] whether files exist, and getting [414:46] information about the current working [414:48] directory and much more. Now, let's dive [414:51] into the practicals. First, we need to [414:54] import the OS module, right? So, import [414:57] OS. We are going to start by checking [415:00] the current working directory. the type [415:03] print os dot get cw. [415:09] Now the get CWD function of the OSI [415:12] module, it returns your current working [415:14] directory where you are currently in [415:16] your file system. So let's execute the [415:19] code. [415:20] As you can see guys, we have this [415:22] output. This is my current working [415:25] directory. Right now let me change my [415:27] current working directory to something [415:29] else. Let's say C drive. [415:32] Now uh let's execute the code. As you [415:36] can see, it has returned my current [415:39] working directory which is now C drive. [415:42] Right? Let me change my current working [415:45] directory back to my previous working [415:47] directory which is Python. [415:52] So yeah, this is as simple as that. It [415:54] returns your current working directory. [415:56] Now I want to to check the contents of [416:01] uh of a directory. [416:04] So os dot list diir. Now list diir uh [416:10] displays the contents of your current [416:13] working directory by default. As you can [416:15] see here I have not provided it any [416:18] specific directory. So if you don't [416:20] provide any directory path then it will [416:23] list contents of your current working [416:25] directory. Let's uh execute the code. As [416:29] you can see this is the contents of my [416:31] current working directory which is this [416:34] Python right now it returns contents in [416:37] a list. As you can see as you can see we [416:40] have the opening and closing uh square [416:43] bracket right it represents a list. So [416:47] all the files and directories are put [416:51] inside a list and each file and [416:54] directory is a separate list item. So as [416:57] you can see this is what I have in my [416:59] current working directory. Now if you [417:01] want to access these items individually [417:05] then we can loop through this list that [417:08] the list diir returns. Okay we can also [417:12] do something like this. [417:15] As you can see it means I am accessing [417:18] the first item from the list that it [417:23] returns. Right? Similarly, I can go for [417:26] let's say three. It will display the [417:29] third item or list item which is files. [417:33] Now let's loop through this entire list [417:39] for i in [417:43] and print [417:46] i. [417:49] Now we have uh looped through each file [417:53] and directory in my current working [417:55] directory. So the way it is working uh [417:57] the list diir function it returns a list [418:00] that list contains all the files and uh [418:04] directories. Right? Then we are using [418:06] the for loop. For loop is going to loop [418:09] through each item one by one. Now [418:15] uh let's uh list contents of a specific [418:18] directory or drive. OS list diir within [418:24] quotes. Specify the drive name or the [418:27] path to your directory. Uh let's say C. [418:32] As you can see guys, this is what I have [418:34] in my C drive. It has listed all the [418:37] contents or files and directories inside [418:40] the C drive in a list as you can see. [418:44] And of course you can loop through uh [418:46] all the items using a loop as we did [418:50] just a minute ago. Right now let I want [418:53] to check the contents of uh a specific [418:56] directory. Let's say the desktop. So [418:58] what I'm going to do is go to my [419:00] desktop. Right click in the bank blank [419:03] space. Click on open in terminal. [419:07] Type uh pwd. Uh it stands for present [419:10] working directory. Let's copy the path [419:13] uh to my desktop directory and then [419:18] let's put it here within quotes. [419:24] Let's execute the code. Okay, we have [419:27] the expected error syntax error. Uni [419:29] code error can't decode bytes. Now the [419:32] error is obvious right here. The list di [419:36] function is is not interpreting this [419:39] backslash as a path separator. It is [419:41] interpreting it as a escape sequence or [419:44] start of an escape sequence. We have [419:46] already talked about it in the in the [419:50] file management section. Right? So to [419:53] get rid of this error just write r [419:57] before the before the quote. It will fix [420:00] the error. [420:02] Now as you can see this is the contents [420:05] of of my desktop directory that I have [420:09] specified here. So that's the list diir [420:13] function. Now let's move on to the next [420:17] useful function that OS module provides [420:19] which is change directory. So chdir [420:24] chdir stands for change directory. It [420:27] allows us to navigate in our file [420:30] system. [420:32] I want to change my directory from my [420:34] current working directory to something [420:36] else. Okay. I want to change my [420:38] directory to to desktop. Okay. So within [420:41] quotes put your directory path where you [420:45] want to switch to or change to and let's [420:49] execute the code. So here I'm telling my [420:53] change DR function that change my [420:55] directory from my current working [420:57] directory to this specified uh path or [421:00] uh directory which is uh the desktop. [421:03] Let's execute the code. As you can see [421:05] it doesn't actually returns any output [421:08] or string. It internally changes your [421:11] your path to the specified uh directory [421:15] which is desktop. Now let's uh check uh [421:18] the current working directory using the [421:21] get cwd method. [421:24] Let's execute the code. As you can see [421:27] guys, my current working directory is [421:29] now desktop because at line number [421:32] three, I'm telling Python that uh change [421:35] my directory to desktop. Then here at [421:38] line number four, I'm printing my [421:40] current working directory which has been [421:42] changed to the desktop. So this is as [421:45] simple as that. [421:49] Next let's see how we can create a [421:52] directory. So print os dot [421:57] make diir. Make diir creates a new [422:02] directory. Now within parenthesis of [422:04] make diir write the directory name that [422:07] you want to create. Let me ls here. [422:12] Now let's create a directory called uh [422:15] demo12. [422:17] So make d uh is going to create this [422:21] specified directory name demo12 in my [422:24] current working directory which is [422:25] python. Let's execute the script. It has [422:29] returned none. This is true because it [422:32] doesn't return any string or output. It [422:35] internally creates the directory name [422:38] that you specify here. Let's ls. As you [422:40] can see, demo12 directory has been [422:44] created. Now I want to create a tree of [422:48] directory means a directory inside [422:50] directory. Now function for uh that is [422:55] make make dirs [423:02] timalu forward slash root. So this make [423:07] d function creates a directory inside [423:11] directory. So it will get directory [423:13] demalu and subd directory root inside [423:16] it. So let's execute the code. none ls [423:21] as you can see dimallu directory has [423:23] been created. Let's check its contents. [423:26] ls uh dimallu as you can see inside [423:29] demalu we have the subdirectory root. [423:32] This way you can create as many [423:34] subdirectories as you like. Like like [423:36] this root 1 2 3. Now this time it will [423:41] create a tree of all these directories. [423:44] Dimalu inside demalu it will create root [423:46] inside root 1 2 3. Then inside 1 2 3 [423:49] directory it will create 54. [423:53] Let's execute the script. ls [423:58] dimallu. As you can see inside imal we [424:01] have uh root and uh inside root we have [424:05] 1 2 3 and inside 1 2 3 we have 454. [424:10] Now let's see how we can uh remove files [424:13] and uh directories with OS module. So [424:18] print os dot [424:23] rm diir r r r r r r r r r r r r r r r r [424:26] r r r r rmd diir is short for remove [424:29] directory as its name suggests it allows [424:33] us to remove a directory. Okay, let me [424:36] create an empty directory make [424:40] root ls. As you can see the the root [424:44] directory has been created. It is an [424:46] empty directory. So let's remove this. [424:48] Now within quotes specify the exact [424:50] directory name that you want to remove [424:55] ls as you can see root directory has [424:58] been removed. Now rmd function is going [425:03] to remove the directory root in in the [425:06] current working directory by default. [425:09] Root directory as as you can see is no [425:11] longer here. Now the limitation of the [425:14] rmd function is that it only removes [425:18] empty directory. If a directory has [425:22] subdirectories or files inside it, then [425:25] it will not be able to remove that [425:27] particular directory. For example, ls [425:30] here. Let me check contents of the files [425:33] directory. Inside the files directory, I [425:36] have this content, right? So let me [425:38] attempt to remove files directory using [425:42] the rmd [425:44] function. So let's provide the name [425:47] files [425:50] ls. As you can see the directory is not [425:53] empty right? It has some contents in it. [425:56] So that's the limitation of the rmd [425:59] directory. Now how to remove directories [426:02] with contents that will be discussed in [426:04] the next video. Right now, let's remove [426:09] a file. [426:11] I'm going to remove this demo .txt file. [426:15] Let's copy it and put it here. [426:23] As you can see, direct the directory [426:25] name is invalid. Obviously, the function [426:28] name says rmd. It only removes [426:31] directories. To remove a file, we have [426:34] the remove function. [426:39] ls. Now I want to remove this uh demo [426:44] dot txt file within parenthesis of uh [426:48] remove put the direct file name that you [426:50] want to remove and it will remove this [426:53] demo. txt in my current working [426:56] directory. ls uh sorry I need to execute [426:59] the code ls now the file has been [427:04] removed right that's how you remove a [427:07] file and uh this remove function only [427:10] works with files it only removes files [427:13] not directories [427:16] now you can remove uh a file at any [427:19] location just specify the path to that [427:22] particular file wherever it is stored [427:25] okay Now the next thing that we are [427:28] going to check if a file or directory [427:30] exists or not. So print os dot path dot [427:38] exists [427:40] exists. [427:42] Now within parenthesis you have to [427:45] specify the file name that you want to [427:47] check. Let's say hello. py. [427:53] Now this exists method checks if the [427:57] specified file hello. py exists or not. [428:02] By default it checks in in my current [428:04] working directory. And obviously in my [428:07] current working directory this hello.py [428:09] file does exist. So let's uh try to [428:12] execute the code. As you can see it has [428:15] returned true. So it returns true only [428:19] if the file or file path that you [428:21] provided exists. Since the hello.py does [428:26] exist. So it has returned true. Now [428:28] let's provide an invalid file name. [428:32] As you can see false. It means the file [428:34] is not present in my current working [428:36] directory. [428:38] Now let me specify path to a file that [428:41] is stored in another location which is [428:44] desktop. So, right click properties. [428:47] Let's check uh copy its path and put it [428:52] here. [428:56] Okay. In desktop, I have this file [429:00] called HDM. [429:03] HDM [429:06] txt. It is very important to specify the [429:09] extension as well. And uh here at the [429:13] beginning write r so that uh python [429:17] doesn't interpret uh the backslashes as [429:21] the start of an escape sequence. So [429:25] let's execute the code. As you can see [429:27] true means this file does exist in my [429:30] desktop or uh this given at this given [429:34] location. [429:35] Now the exists method also checks for uh [429:39] for a directory [429:42] ls. Okay, let me resize the terminal [429:48] ls. Now here as you can see I have this [429:51] files directory. So let's provide the [429:54] files directory name. [429:59] As you can see true means the files [430:01] directory exists. So it checks for both [430:04] files and directories. Uh now what I'm [430:07] going to do is remove the file name [430:10] and uh see what it returns [430:19] and we have true because this desktop as [430:22] you can see this is a directory since [430:24] this directory does exist so it has [430:27] returned true. That's how we use the [430:29] exists method. Now another important [430:32] function that OS module provides is [430:36] name. Now the name returns name of your [430:40] operating system. Okay, here we don't [430:43] need to put the parenthesis like this. [430:46] Just OS.NAME. [430:48] Uh let's execute the code. As you can [430:49] see means this is a Windows operating [430:54] system. [430:55] Now let's see how we can execute [430:58] commands uh inside your Python scriptor. [431:02] So we have os dots system [431:07] function. It allows us to execute [431:10] commands within parenthesis. Write the [431:13] command that you want to execute. Let's [431:15] say diir. [431:17] Let's execute the code as you okay. Did [431:21] you mean system? Okay. Uh spelling [431:24] mistake here system dir [431:30] command uh displays contents of a [431:33] directory. Right? So let's execute the d [431:36] command first. As you can see this is [431:38] the contents of my current working [431:40] directory. Now I'm executing the same [431:42] command inside my python program. So it [431:45] will produce the same output. So let's [431:47] execute the [431:50] program. As you can see, it has listed [431:52] contents of my current working [431:55] directory. This way you can execute any [431:58] command in your uh inside your Python [432:01] script. Just write the command name [432:04] within the quotes. Now to execute a [432:07] PowerShell command, we have to write the [432:10] PowerShell [432:13] before the actual command like this. [432:14] PowerShell [432:16] then uh let's execute get process [432:20] command. Get process command in [432:22] PowerShell displays all the running [432:24] processes on a system. Now if you want [432:26] to learn more about uh PowerShell then I [432:30] have included the PowerShell in my cyber [432:33] security course that that you can you [432:36] know check out if if you if you want to [432:38] dive deeper into the PowerShell. [432:41] Now it is going to display all the [432:43] running processes in my system. [432:47] As you can see guys, this is the get [432:49] process command. Similarly, you can [432:51] execute any PowerShell command. Let's [432:53] say get service and it lists all the [432:57] services. [432:59] Okay, spelling mistake guys. Service. [433:03] Now it will list all the services like [433:05] this. So that's it for this video guys. [433:08] Thank you very much for watching. Let me [433:09] know if you have any questions. In this [433:11] video we are going to take a look at the [433:14] shuttle module. It stands for shell [433:16] utilities. It provides highle operations [433:20] for working with files and directories [433:23] such as copying, moving, and deleting [433:25] them. Similar to the OS module. However, [433:28] as we saw in the previous video, the OS [433:31] module has one limitation that it [433:34] doesn't allow us to remove directories [433:37] that contain files or subdirectories. [433:40] Functions like OS, RM, DI can only [433:44] delete empty directories. Using shuttle [433:47] module, we can remove an entire [433:49] directory along with all its files and [433:53] subdirectories in a single operation. It [433:55] is more flexible, more advanced and [433:58] especially useful when working with [434:00] entire folders or large scale file [434:03] operations. With shuttle you can copy [434:06] individual files, copy complete [434:07] directories including subfolders, move [434:10] or rename files and folders, delete [434:14] directories along with all their [434:16] contents. Now let's dive into the [434:19] practicals. Uh first we have to [434:21] obviously import the module itself [434:24] shuttle. Now we are going to start by [434:27] copying files and directories. Let me [434:30] ls. Now the OS module that we covered in [434:34] the previous video has one obvious [434:36] shortcoming. It does not allow us to uh [434:40] copy files and directories. So we are [434:42] going to start by copying a file. I'm [434:44] going to copy this hello.py file. Let me [434:47] copy the file name. Now type shuttle [434:52] dot [434:54] copy. Now the shuttle has a few options [434:58] for copying a file such as copy copy to. [435:01] Now we are going to use the copy to uh [435:04] method because it not only copies the [435:07] file, it also copies its metadata. [435:10] Metadata is basically the details of a [435:13] file such as its permissions uh last [435:16] modified date and time ATC. So shuttle [435:19] dotcopy to. Now we have to tell the copy [435:22] to uh function two things. The file name [435:26] that you want to copy and the [435:28] destination directory where you want to [435:30] copy. I want to copy this hello.py [435:34] file uh which is in my current working [435:36] directory. So let me paste it here. [435:39] Comma. Now specify the destination [435:41] directory. I'm going to copy in my same [435:42] directory. So uh let's give it a name. [435:46] Hello CP. cp [435:49] py. So what the copy function is going [435:51] to do? It will take this file and create [435:55] a copy of it under this new name hello [435:58] ccp. py. Now by default the copy command [436:02] searches for the file in in your current [436:05] working directory. So it will search for [436:07] this hello.py file in my current working [436:10] directory. If it finds this file, then [436:13] it will make a copy of it under this new [436:17] name in the same directory or in my [436:20] current working directory. Let's uh [436:22] execute the script. We have no errors or [436:27] output. Now let's ls. As you can see [436:30] guys, okay, as you can see, we have [436:33] successfully created a copy of this [436:36] hello uh pi file under this new name. [436:39] Now uh we can copy a file to any [436:43] directory. Let me copy this to my [436:46] desktop. So right click uh uh in in [436:50] desktop open in terminal. I want to copy [436:54] my complete path to the desktop which is [436:57] this. [437:00] Now let's uh paste the path here [437:05] and put r before the opening double [437:08] quote so that uh copy to doesn't confuse [437:12] the path separator backslash with a [437:14] start of an escape sequence. This time [437:17] I'm telling this copy to method that [437:19] take this file which is in my current [437:21] working directory then make a copy of it [437:25] in my desktop or whatever path you [437:28] specify. Let's execute the code and uh [437:34] and we have no error. And let's check my [437:37] desktop. As you can see guys here, hello [437:40] this is a Python file. It has been [437:42] copied. Now we can copy the same file [437:45] under a new name as well after the [437:48] directory name slash write uh [437:52] the file name hello [437:55] dot py. This time it will make a copy of [438:00] this hello.py file in desktop under this [438:03] new name. Let's execute the code. And [438:07] here as you can see hello 12 has been [438:09] copied to the desktop. So that's how you [438:12] can copy a file. Now let's copy [438:16] a directory ls. [438:19] Uh let me check contents of the files. [438:22] directory ls files. [438:26] Inside the files, as you can see, I have [438:29] all these files, right? So, what I want [438:32] to do is make a copy of this files [438:36] directory. So, [438:38] patil [438:41] dot [438:42] copy [438:44] tree. Now the you know to copy [438:48] directories and uh uh their contents we [438:51] have the copy tree function. Copy tree [438:53] function not only copies a directory it [438:56] also copies contents of that directory. [438:59] Now let's provide the directory name [439:02] that we want to copy. As you can see in [439:04] my current working directory I have this [439:06] files directory. I want to copy [439:10] uh this files directory, [439:14] and uh files one two. So what copy tree [439:19] is going to do? It will take files [439:22] directory in my current work from my [439:24] current working directory and create a [439:26] copy of it under this new name files one [439:30] two. So all the contents of this files [439:33] directory will be copied into this files [439:36] one to directory [439:39] l uh let's execute the script first ls [439:43] as you can see we have the files one to [439:46] directory let's check its contents files [439:48] one two and we have successfully copied [439:52] not only these files also its contents [439:55] right and similarly you can uh copy a [439:59] directory to any specific directory. [440:02] Just provide the complete path and uh [440:06] then it will copy the directory to that [440:10] specific location or directory. Now [440:13] let's see how we can remove a directory [440:16] along with its contents. As we saw in [440:19] the previous video, the OS module allows [440:23] us to remove only an empty directory, [440:26] right? uh we can't remove a directory [440:28] with contents with OS module but with [440:31] the shuttle module we can remove [440:34] everything. Shuttle dot rm [440:39] tree. [440:41] Now rm tree is short for remove tree. It [440:44] means it not only removes a directory, [440:46] it also removes its contents. For [440:49] example, ls [440:51] here I have this directory called files [440:53] one two ls files one two. Now inside the [440:58] files directory I have all this content [441:01] or these files. So I want to get rid of [441:04] this files directory along with its [441:06] contents. So within quotes [441:09] specify the exact directory name which [441:13] is files one. So, rm tree will remove [441:16] this files one to directory along with [441:20] its contents. Okay, let's execute the [441:23] code [441:25] and we have no errors. Let's say ls. As [441:29] you can see the files one to directory [441:31] has been removed. Similarly, you can [441:34] remove [441:36] a directory from any specific location [441:39] or directory. Just specify the complete [441:42] path to that directory. Now we are going [441:46] to move files from one location to [441:50] another just like the cut and paste. [441:54] Okay. Sorry. LS. Let's say I want to [441:57] move Hello CP from my current working [442:00] directory to demo one two. So let's [442:03] check contents of demo one two. Okay, it [442:05] is an empty directory. [442:08] Now function for moving is simply move. [442:15] So specify the file name that you want [442:18] to move which is hello cp for me. [442:24] Now the second parameter must be a [442:27] directory. So directory name is demo [442:31] 12. [442:35] So move uh is going to take this hello [442:38] cp.py file and move it into this [442:41] directory demo one2 which is in my [442:44] current working directory. Remember this [442:46] file is in my current working directory [442:48] and this directory is also in my current [442:51] working directory. So let's execute the [442:55] code. Okay, we have no errors. ls as you [442:59] can see hello cp is no longer here. But [443:02] if I check contents of uh demo one two [443:06] and it has been moved here. Now let's uh [443:11] move [443:13] this user data.txt [443:15] to to my desktop. So let's copy the [443:21] path to my desktop. pwd. [443:28] This time the destination path is going [443:30] to be this. And of course we have to [443:33] specify r at the beginning. And make [443:36] sure that your path is closed properly [443:39] like this. This time I'm telling move [443:42] function that uh take this file user [443:45] data dot txt. Let me put it here first. [443:48] So move function is going to take this [443:52] specified file user data.txt txt and [443:56] then move it into the desktop or [443:59] whatever location you specify. Let's [444:02] execute the code. [444:05] Okay, we have no errors. But if I check [444:07] my desktop, as you can see the file user [444:09] data has been moved to the desktop. [444:13] Let's ls we no longer have the user [444:16] data.xt file here. It has been moved to [444:19] the new location desktop. [444:22] Welcome everyone. Now we are going to [444:24] create some very useful Python real [444:26] world projects in this and next few [444:30] sections. These projects will help you [444:33] apply all the concepts you have learned [444:35] throughout this course in a practical [444:38] and meaningful way. By building [444:40] projects, you will strengthen your [444:43] problem solving skills, improve your [444:45] coding confidence, and see how different [444:48] Python concepts work together. It's time [444:51] to solidify your understanding of Python [444:54] and start thinking like a real [444:57] developer. Now, in this particular [444:59] project, we will build a password [445:01] generator that generates strong [445:04] passwords. This is a simple project [445:06] which is designed to help you understand [445:08] the logic behind randomness and string [445:12] manipulation in Python. As we move [445:14] forward, the complexity of our projects [445:18] will increase which will help you grow [445:21] step by step as a Python programmer. So [445:24] let's dive into the practicals. Now [445:26] let's dive into the practicals and [445:29] import the random module. We are going [445:32] to use the random module to generate [445:34] password. Now our program will give [445:37] users the ability to generate password [445:40] of their desired length. For example, if [445:43] a user wants to generate password that [445:46] is 15 characters long, then they should [445:48] be able to do it. Okay. So, let's create [445:52] a variable peng equal to input. [445:57] Enter the password length. [446:04] So this p length variable is storing the [446:07] password length whatever uh password [446:10] length the user wants. Now we are going [446:12] to create a function that will generate [446:14] the password. So function name is going [446:17] to be pass [446:19] gen. Now we are going to pass the [446:22] password length as an argument to the to [446:24] this pass gen function. [446:30] Now let's define the passgen function. [446:33] define [446:35] passion. Now here this past chain [446:37] function as you can see we are passing [446:39] it the p length as an argument. So this [446:43] argument needs to be accepted here. So p [446:47] length. [446:49] Now inside this pass chain function [446:51] first we need to initialize a few [446:53] variables. So first variable is going to [446:55] be password equal to nothing. So we have [446:58] created the variable password. It is [447:00] equal to nothing. The reason why it has [447:02] been initialized with nothing because [447:06] this variable is going to store the [447:09] actual password. We will be appending or [447:12] concatenating the random characters that [447:15] a random module is going to generate to [447:17] this pass WD variable. That's why it has [447:20] been initialized with nothing. Now let's [447:24] create uh care set variable. The car set [447:28] variable is going to store the [447:30] characters that we are going to use to [447:32] generate the password. We are going to [447:34] use all the 26 characters. So type them [447:36] in here. [447:41] And of course we will be using all the [447:42] 10 digits. [447:44] And our password is also going to [447:47] contain a special character. It is [447:50] mandatory to have at least one special [447:52] character in a secure password. Okay, [447:55] that special character is going to be [447:57] the underscore. So, underscore and [448:00] hyphen as well. So, these are the [448:02] characters that we will be using to [448:04] generate the password. Okay. Now, let's [448:08] create a loop for i in range. [448:13] Loop will start from one and run up to [448:17] the number that the user enters. For [448:19] example, if user enters 12, then this [448:22] loop will run uh 12 times and it will [448:25] generate the password that is 12 [448:28] characters long or whatever number the [448:31] user enters. So second value needs to be [448:35] the value that we have passed to this [448:37] function. So here we are passing p [448:40] length right and we are accepting this [448:42] argument as a parameter here inside the [448:46] passion function pen right. So write the [448:50] password length here + 1. Now write [448:55] password equal to [448:59] password. Now this password variable as [449:02] you can see this is the variable that I [449:04] have initialized here. So make sure that [449:07] you write that variable here. Password [449:08] equal to again password [449:11] plus now let's uh generate a random [449:15] character. So random dot choice. Now the [449:18] choice variable as we already know sorry [449:20] the choice function of the random [449:22] function as we already know it selects a [449:25] random character from a given character [449:28] set. We are going to provide it the care [449:31] set variable. So [449:34] care set the car set variable as you can [449:36] see it is storing all these characters. [449:39] Okay let's uh print the password [449:42] variable then I I'll break down [449:43] everything. Okay, password. [449:48] Let's execute the code. [449:56] Enter the password length. Let's say 12. [449:59] As you can see, we have uh an error. [450:01] Type error can only concatenate string [450:05] not int at line number seven. Okay. [450:07] Okay. Let's see line number seven. [450:10] Okay. Okay. Here as you can see I'm [450:13] passing the number that user enters to [450:16] the pass gen function. Now as we already [450:19] know the input function treats all [450:22] inputs as a string. Whether you enter [450:25] integers, decimal numbers or boolean [450:29] data, it treats everything as a string. [450:32] So we need to fix it and convert this [450:35] string into an integer. It can be done [450:38] right here or where you are asking for [450:41] user input. So let's do it here. Int and [450:47] close the int [450:50] at the end like this. Now it should it [450:52] should fix the error. [450:54] Let's execute the code. Let's say 13. As [450:57] you can see guys, we have generated the [451:00] password. We are not there yet of course [451:03] but we certainly have uh made some [451:05] progress here. So let's break this down. [451:08] It is important to understand how it is [451:11] uh working in the background. [451:13] So first thing that we are doing is [451:15] asking user to enter password length. [451:18] How long they want their password to be [451:21] right? So whatever length or number user [451:24] enters let's say here I have entered 13 [451:27] that gets stored in the pen variable. [451:29] Now we are passing the peng variable as [451:32] an argument to passion. And here we are [451:35] accepting that argument as a parameter. [451:38] And here we have created these two [451:41] variables. The password variable is [451:42] storing nothing and character set [451:45] variable is storing these characters. [451:48] Right? Now here we have created this uh [451:50] for loop. It starts from one and runs up [451:54] to the number that the user enters. Here [451:57] we have entered 13. So this loop will [452:00] run 13 times. And on each run we are [452:05] generating a random character then [452:08] concatenating that random character to [452:10] the password variable. Okay. So when [452:13] this loop runs for the first time we are [452:16] generating the first character. First [452:19] Python resolves this particular part. So [452:22] random dot choice. So choice the choice [452:25] function is going to select a random [452:27] character from this given character set [452:30] which is car set. So car care set is [452:32] storing all these characters. So on the [452:36] first run it is going to select the [452:38] first random character which is this. [452:42] Right? On the first run the choice [452:43] function selects the E character. Then [452:47] we are concatenating password with the [452:50] generated character which is E. Now the [452:52] password variable for now is storing [452:54] nothing. It is storing an empty value. [452:57] Right? So here this addition operator it [453:00] concatenates the e with the past wd [453:05] variable which is storing nothing. So e [453:07] gets concatenated into the pass wd [453:10] variable. Then that uh concatenated [453:13] value is stored in the past wd variable. [453:16] Now the past wd is storing e and down [453:20] here we are printing the e. That's why [453:22] we have e in the output. And when this [453:24] loop runs for the second time, the [453:26] choice function selects one and then we [453:31] are concat concatenating one to the past [453:34] WD. Now pass WD is already storing E. So [453:38] one gets concatenated with E, right? [453:42] Then that concatenated value gets stored [453:45] in the past variable. Now past WD [453:47] variable is storing these two values. [453:51] And when this loop runs for the second [453:53] time, the choice function generates or [453:56] selects the random character six and six [453:59] gets concatenated to the password. [454:01] Password variable is already storing [454:03] these two characters. So on the third [454:06] run, it is going to concatenate six to [454:09] the pass WD variable and then we are [454:12] printing that value here. So okay, so [454:15] this loop runs 13 times. On each run it [454:18] selects a random character. That random [454:21] character gets concatenated to the pass [454:24] WD variable. Right? So at the end as you [454:27] can see it has generated the 13 random [454:31] characters because the password length [454:33] is 13. So this loop ran 13 times and on [454:36] each run it selected or generated a [454:39] random random character then [454:40] concatenated them together. Now here it [454:43] is important to notice that uh we are [454:45] using plus to concatenate. When you use [454:49] plus with two values, two string values, [454:52] it concatenates them. Right? Okay. Let's [454:56] uh check the length [455:00] for the confirmation. [455:04] Let's enter 12. As you can see, password [455:08] length is 12. Right? Now let's print [455:12] this uh password outside of the for loop [455:15] uh for loops scope like this. Now we [455:18] should only have the [455:21] uh final password as you can see. [455:24] Okay, that's it for this video. In the [455:26] next video we will further refine this [455:29] this code. Obviously this is a very [455:32] incomplete program. We are going to [455:34] continue where we left off in the [455:37] previous video. In this video, we will [455:39] perform some validation. Uh let me [455:42] execute my code and enter let's say two. [455:47] As you can see, the program has [455:49] generated the password that is two [455:51] characters long because that's what I [455:53] asked my program to to do. However, a [455:56] secure uh password has some minimum [455:59] requirements, right? A secure password [456:02] has to be minimum 8 characters long or [456:06] maybe 10 characters long. So this is [456:08] what we are going to uh do the next we [456:11] will generate the password only if the [456:15] user enters the number eight or more. [456:19] Your password can't be less than 8 [456:22] characters long. Okay. So let's write if [456:27] sorry if p length is less than uh let's [456:33] say 8 then we are going to print the [456:37] message your [456:41] password [456:43] must be 8 characters [456:50] long must be minimum [456:57] eight characters long [457:00] and then write the exit function. Now [457:03] the exit function in Python exits out of [457:06] the program. It terminates your program. [457:08] Okay, so let me execute the code. [457:13] Okay, let's enter let's say six. Press [457:16] enter. As you can see your password must [457:18] be minimum 8 characters [457:21] long. Okay. So I entered six. Here I'm [457:25] performing the condition check if the [457:27] password length is less than 8. Now [457:30] since I entered six, six got stored in [457:33] the p length. So here I'm checking if p [457:36] length which is storing six is less than [457:38] 8. Condition is true. Right? 6 is less [457:40] than 8. So condition was evaluated to [457:43] true and the block of if was executed [457:46] where I printed this message. Then here [457:50] I'm using the exit function. So exit [457:52] function exits out of your Python [457:55] program. As soon as your exit function [457:58] gets executed, your program stops right [458:01] there. Your program gets terminated [458:04] there. So now let's enter let's say [458:08] eight. Your password must be minimum 8 [458:10] characters long. Okay. Here what we can [458:13] do is remove the equal to sign. Now it [458:17] will generate the password that is 8 8 [458:21] characters long. As you can see [458:25] I entered eight. Now it has generated [458:28] the password that is 8 characters long. [458:32] So you must enter eight or more then it [458:36] will generate password. that password. [458:38] You can modify this value however you [458:41] like. Maybe you want your password [458:44] length minimum five. You can do that as [458:47] well like this. If I enter five, okay, [458:51] it is generating [458:54] the password that is five characters [458:56] long. But if you enter anything less [458:58] than five then yeah it will show this [459:02] error and ask you to enter password that [459:05] is at least uh 8 characters long or [459:08] however many characters you want. In the [459:11] next video we are going to finish this [459:13] program. Okay. Okay. We are continuing [459:16] where we left off in the previous video. [459:20] Now here I'm using the print function to [459:22] print the password. Now I'm not going to [459:24] print the password inside the functions [459:27] block rather I'm going to return the [459:30] password. So return [459:34] return [459:35] password. So I'm returning password back [459:38] to the part where I'm calling the [459:41] function. So down here I'm calling my [459:43] function here right [459:46] now. So password [459:50] equal to pass gen [459:54] and let's print the [459:57] password [460:00] let's say 12. Okay, we are uh able to [460:02] generate and print the password. So guys [460:06] the way it is working here at line [460:08] number 18 I have uh this line password [460:11] equal to pass gen which is a function. [460:14] So, so first Python calls this function. [460:16] Once a function is called, the execution [460:19] moves to the part where you have defined [460:21] the function. So, here uh we have [460:24] defined the function. So, here Python [460:27] generates the password then returns that [460:31] password back to the passgen function [460:34] where it has been called. It has been [460:36] called here. Now we are storing the [460:39] returned value which is the password in [460:42] this variable called password. Then we [460:44] are printing that uh that value here. [460:47] Okay. Now we need to to do a few fixes. [460:50] Let's say I want uh my password only in [460:53] uppercase. So what we can do is uh [460:57] password is storing the actual password [461:00] right? So we have we can use the [461:02] uppercase function to convert the [461:05] password into uppercase characters as [461:08] you can see right [461:14] let's enter password that is 44 [461:16] characters long okay so this way you can [461:19] you know mix up your password you can [461:20] use upper case and only lower cases as [461:23] well now let's say I want to generate [461:27] maybe 10 passwords Let's uh then write [461:31] for i in range [461:36] and loop is going to start from one and [461:38] run 10 times 10 + 1. Now inside the [461:42] block of uh for loop we need to call the [461:46] function. Okay. So this loop obviously [461:48] okay 10 + 1 it it is going to run 10 [461:52] times. So when this loop runs for the [461:54] first time we are calling the function [461:56] right it uh this function generates the [462:00] password then returns that password to [462:02] the function then we are storing that [462:05] password to the password variable and [462:08] here I'm printing that password right [462:14] as you can see we have generated 10 [462:16] passwords right now when this loop runs [462:19] uh for the second time uh it is going to [462:22] repeat the same thing. It will call the [462:24] function. This function will generate [462:26] the password and return the generated [462:28] password uh to the function pass gen. [462:32] Then we are assigning the gen the [462:34] returned value to the password again. [462:36] And uh then we are printing that value [462:39] here. So since this loop runs 10 times, [462:43] this function gets called 10 times and [462:45] each time it generates a new password [462:48] and uh yeah, then we are storing that [462:51] password here and printing that out like [462:54] this. Let's generate let's say 20 [462:56] passwords. [462:59] Okay, sorry. This is the password [463:00] length. So it has generated 10 passwords [463:03] that are 12 20 digits long. If you want [463:06] to generate let's say 20 passwords then [463:08] you have to provide that value to the [463:11] here to the for loop like this. Now this [463:13] will generate [463:16] 20 passwords and one important thing [463:19] before signing off is this return value. [463:22] Now make sure that you return the [463:26] password outside of the block of for [463:29] loop like this. Okay, this as you can [463:32] see here I'm returning it outside of the [463:35] for loops block because here it is going [463:38] to return the complete password. But if [463:42] you put the return uh inside the for [463:45] loops block then it will create problems [463:49] as you can see. So what basically is [463:51] happening? So when this loop runs for [463:53] the first time it generates the first [463:55] character and gets stored in the past wd [463:59] variable. then it is returning that [464:03] generated character to the function. [464:05] Then uh we are you know storing that [464:08] here and printing it out. So the rule of [464:11] the return return is that as soon as the [464:14] return gets executed it will not execute [464:17] any lines after it and control [464:20] immediately moves to the part where the [464:22] function has been called. Okay. So make [464:25] sure that the value is returned outside [464:28] of the for loops structure. This way it [464:30] will return the complete password like [464:33] this. So yeah guys that's it for this [464:36] small project. Let me know if you have [464:38] any questions and of course you are [464:40] absolutely free to improvise this [464:42] project and add the features that you [464:44] that you want. This project is an [464:47] extension of our previous project. Now [464:50] we are building a MAC address address [464:52] generator that can create either a [464:56] single MAC address or multiple MAC [464:59] addresses at once. This program requires [465:02] a bit more complex logic than the [465:04] previous one because it involves [465:07] grouping characters into pairs and also [465:10] managing separators. This will enhance [465:13] our understanding of loops and string [465:16] manipulation in Python. So let's dive [465:18] into the practicals now. Let's dive into [465:21] the practicals. Before writing the code, [465:24] let me uh let me show you how a MAC [465:27] address looks like. So press Windows key [465:30] and type PowerShell. Click on PowerShell [465:33] 7 or 5 whatever appears the first. Now [465:38] uh type the commandlet get- [465:42] net adapter. Press enter. This get net [465:46] adapter. Commandlet lists all the [465:49] installed network interfaces. Now we [465:52] need to check out this MAC address [465:54] column. These are the MAC addresses [465:58] right for each interface. A MAC address [466:01] contains 12 hexadesimal digits and uh [466:05] the hexadimal digits are grouped into [466:08] the pairs of two. So we have six pairs [466:11] of these hexadesimal digits and pairs [466:14] are separated by hyphens. As you can [466:17] see, however, on Windows and Linux, [466:20] these pairs are separated by columns. [466:23] So, what I'm going to do is copy a MAC [466:25] address and uh [466:29] put it inside my code editor. [466:32] Now, here we need to use a bit a bit of [466:35] logic, right? We have to keep track of [466:38] of digits. So after every second digit [466:41] we have to append this hyphen character [466:45] to the MAC address. We are going to use [466:47] the [466:49] random module to generate MAC address or [466:53] addresses. Now I'm going to create a [466:56] function that will actually generate the [466:58] MAC address. So MAC [467:01] gen MAC generator. You can give any name [467:05] to your function of course. Now let's [467:07] define this function. This function is [467:09] not going to accept any arguments. [467:12] Arguments are not required for this [467:14] function. So define. So let's define [467:17] mac [467:19] gen. [467:21] We need to create a few variables. So [467:25] first variable is going to be mac header [467:29] equal to nothing or an empty string. [467:33] This MAC adder variable is going to [467:35] store the actual or the final MAC [467:38] address. Now uh let's create a variable [467:41] called count. Count count equal to zero. [467:43] Now this count variable is going to keep [467:46] track of pairs. So after generating two [467:49] digits, we are going to append this [467:52] hyphen character to the MAC address. So [467:55] this count variable is going to count [467:58] these pairs. So after every second digit [468:01] we will have to append the hyphen [468:03] character. Now write uh create variable [468:07] called care set. Car set variable is [468:09] going to store the characters that will [468:13] be used to generate the MAC address. As [468:16] you can see a MAC address is made up of [468:20] hexadimal digits. So write the hexadimal [468:24] digits. Write all the nine sorry 10 [468:28] digits from one to uh from 0 to 9 and [468:31] six hexadesimal digits or characters [468:36] from A to F A B C D E F. So this is the [468:41] character set that we are going to use [468:42] to generate the MAC address. Now let's [468:45] create a loop [468:47] for I in range. This loop runs 12 times [468:52] uh because a MAC address contains 12 [468:55] digits. So we will have to generate 12 [468:58] random digits. So on each run this for [469:02] loop is going to generate a random [469:04] hexadimal digit. So from 1 to 12 + 1. [469:12] Now write Mac adder equal to now this [469:16] MAC adder is the variable that we have [469:18] initialized here for now it is storing [469:21] an empty string. So MAC adder equal to [469:24] Mac adder plus now let's generate a [469:29] hexadimal digit. So random [469:33] sorry random [469:36] random dot choice. Now the choice [469:39] function as we already know it selects a [469:43] random character from a given character [469:46] set. Now we are going to give it this [469:48] character set and this is stored in the [469:51] variable care set. So I'm going to copy [469:53] the variable care set and put it here. [469:58] Let's print the MAC header. [470:01] Let's execute the code. Then I will [470:02] break down everything. Okay. Okay. It is [470:04] working just fine as it should. So it [470:08] has generated 12 hexadesimal uh digits. [470:12] So this loop runs 12 times. Right? So [470:15] when this loop runs for the first time, [470:17] MAC adder is equal to Mac adder plus [470:21] random dot choice. First Python is going [470:23] to resolve this portion. So here the [470:26] choice function will select a random [470:30] character from this given care set. [470:33] Right? From this given care set. So on [470:35] the first run it selects four. Now after [470:39] selecting four it is going to [470:41] concatenate four with the mac adder [470:45] variable. Now mac adder variable for now [470:47] is storing nothing. Now after [470:50] concatenating nothing with four the [470:53] value of mac adder variable becomes [470:56] four. So that [470:58] concatenated value is assigned to the [471:01] mac adder variable. Now we are printing [471:04] the macader variable that's why four got [471:07] printed. Now when this loop runs for the [471:10] second time the random choice function [471:13] selects the second digit which is 8. [471:17] Right? Now this 8 is concatenated [471:21] into the mac adder variable. Now mac [471:24] adder is already storing four. Right? So [471:28] 8 get concatenated with the four. Now [471:31] this concatenated value is assigned or [471:34] stored in the macad variable. Now macad [471:37] variable is storing 48. So we are [471:39] printing 48. Here on the third run it [471:42] selects random dot choice selects seven [471:45] right and seven gets concatenated to the [471:48] existing values 4 8. So it keeps [471:51] repeating this process uh 12 times [471:54] because this loop runs 12 times. On each [471:57] run the random dot choice function [472:00] selects a random character and then we [472:04] are concatenating that random character [472:06] to the to the mac adder variable. So [472:10] therefore at the end we have this [472:12] complete number that is 12 hexadimal [472:15] digits long because this loop runs 12 [472:18] times. Right? So yeah, we have created [472:20] our core program and in the next video [472:23] we will append the hyphen after every [472:27] second digit. Okay, so that's it for [472:30] this video. I'm going to resume where I [472:32] left off in the previous video. In this [472:35] video, I'm going to append this hyphen [472:39] after every second digit like this. [472:42] Right, I have created count variable for [472:45] this particular purpose. it is going to [472:47] keep track of the digits right after [472:50] every second digit we will append this. [472:53] Okay. So inside the for loop make sure [472:55] that you have uh the count variable [472:57] being initialized to zero and inside the [473:00] block of for loop we need to count this [473:03] variable by one. So count equal to count [473:06] + 1. So what is going to happen whenever [473:10] this loop runs on each run the value of [473:14] count will be incremented by one. So [473:16] let's check if count equal to two. So [473:20] when the value of count becomes two we [473:23] are going to append the hyphen to the [473:27] mac adder variable. So, MAC adder equal [473:31] to [473:33] Mac adder plus let's append this hyphen. [473:39] Okay. So, first let's execute the code [473:41] then I will break down everything. As [473:43] you can see after uh second digit it has [473:47] appended hyphen. However, it has not [473:49] appended it after other pairs right? It [473:53] is only working with the first two [473:55] digits or the first pair. Why? Because [473:58] when this loop runs for the first time [474:00] at line number 11, we are incrementing [474:04] value of count which is zero by 1. So [474:07] count + 1. 0 + 1 becomes 1. Now the [474:10] value of count is 1. Here the choice [474:13] function is going to uh select a random [474:16] character and store that in the macad [474:19] variable. Right here I'm checking if [474:22] count is equal to two. It is false. [474:24] Counts current value is one. So one is [474:27] is not equal to two. So this block will [474:31] not be executed. And here we are [474:34] printing e. Now control moves back to [474:36] the for loop. Here it will again [474:38] increment the value of count by one. The [474:42] current value of count is 1. So 1 + 1 [474:45] becomes two. Now the count's value is [474:49] two. And uh here choice is going to [474:53] select a random character which is zero. [474:56] and uh concatenate it with the MAC [474:59] header which is already storing E. So [475:02] MAC adder is now storing E and zero. Now [475:06] here I'm checking if count is equal to [475:08] two. Condition is true, right? Count's [475:10] current value is two. So 2 is equal to [475:13] two. Since this condition is evaluated [475:16] to true, the block of if is executed. [475:19] Now inside the block of if I am [475:22] appending MAC adder equal to Mac adder [475:26] plus [475:27] hyphen right so hyphen gets appended to [475:32] this MAC adder variable which is this. [475:36] That's why we have the hyphen here. So [475:39] we are printing it here. Now when this [475:41] loop runs for the third time value of [475:45] count becomes three. So this random [475:48] choice selects the third character and [475:51] it gets appended to the MAC header. Now [475:54] condition is false. Count whose value is [475:57] three. Three is not equal to two. So [475:59] this will not be executed on the fourth [476:01] run. The value of count becomes four. It [476:05] choice selects the fourth character and [476:08] it gets appended to the macader. And [476:11] here I'm checking count whose value is [476:13] four equal to two. Condition is again [476:16] false. So the problem here is with the [476:19] count variable. So what we need to do [476:21] after the value of count reaches two. We [476:25] need to reset it. Uh inside this uh if [476:29] conditions block, we are appending the [476:32] hyphen to the MAC header if the value of [476:36] count reaches two. Now we need to reset [476:39] it to zero again. Okay. Uh so when value [476:43] of count reaches two we are appending [476:45] the hyphen to the macader variable and [476:48] then resetting or reinitializing the [476:51] value of count zero so it can track the [476:56] next two digits. So this time it should [476:59] uh fix the error. [477:03] As you can see guys now after every [477:05] second digit we are appending the [477:07] hyphen. Okay we have hyphen at the end [477:09] as well. Uh don't worry about it. It [477:12] will be fixed later. So we are getting [477:15] closer. Right in the next video we we [477:18] will clean up and format our MAC [477:20] address. We are going to continue where [477:23] I left off in the previous video. Now [477:25] first thing that I'm going to do is uh I [477:28] don't want to print the every character [477:31] uh that this uh this function is [477:34] generating. So remove the print function [477:38] and I'm going to return the [477:43] MAC address [477:45] like this. Okay, make sure that the [477:47] return statement is outside of the for [477:51] loops uh for loops block like this. Now [477:55] let's uh print the value [477:58] that that is being returned. [478:04] Okay, it is returning a MAC address, [478:07] right? As you can see. Now, what I'm [478:09] going to do is uh assign the returned [478:11] value to a variable [478:14] MAC equal to [478:18] print [478:20] Mac. [478:23] Now I need to get rid of this particular [478:26] part, right? This is not required. So [478:30] Mac [478:33] I'm going to slice this last portion [478:37] minus one. [478:40] Now we have the desired output. Now MAC [478:43] address as you can see the letters are [478:46] in uppercase. So what I'm going to do is [478:48] convert the lowerase [478:52] characters into letters into uppercase [478:55] using the upper function. And we have [478:58] successfully converted the lowerase [479:02] uh letters into upper case. Right? Now [479:05] let's generate multiple MAC addresses. [479:07] So what I'm going to do is uh write a [479:10] for loop. [479:12] Uh I want to generate 20 addresses. So 1 [479:18] 20 + 1 [479:22] and write these two lines inside the [479:26] block of for loop like this. Let's [479:29] execute the code and we have [479:31] successfully generated 20 MAC addresses. [479:35] So the way it is working this loop runs [479:37] 20 times right. So when this loop runs [479:39] for the first time here I am assigning [479:43] MAC address equal to MAC variable. Now [479:46] MAC this is obviously a function. First [479:48] Python is going to execute this [479:50] function. Here we are calling the [479:51] function. First Python is going to call [479:53] this function control moves here where [479:55] we have defined the function and here it [479:58] will generate the MAC address then [480:00] return the generated MAC address to the [480:02] function. Then I'm assigning the [480:05] returned value to the MAC variable. And [480:08] here I'm slicing the last character from [480:11] this variable which is uh which is this [480:14] right? If you remember at the end we had [480:18] this unnecessary hyphen. So it basically [480:22] slices the last character. Then I'm [480:25] using the uppercase function. So [480:28] uppercase function is going to convert [480:30] all the lowerase letters to uppercase [480:34] that's why we have everything in [480:35] uppercase. So we have successfully [480:38] generated created the MAC address as [480:41] well as we are generating 20 MAC [480:43] addresses. And this way you can generate [480:45] as many MAC addresses as you like. Just [480:49] write that number in the loop. This time [480:52] uh this for loop runs 10 times. So [480:56] it will generate sorry this loop runs [480:59] 100 times. So it is generating 100 MAC [481:02] addresses. So on each run this function [481:05] gets called. It returns a MAC address. [481:07] Then we are printing that that MAC [481:09] address. Now let's take this one step uh [481:13] forwarder. [481:15] I'm going to save the MAC addresses in a [481:20] file. Okay. So here we are generating [481:22] these MAC addresses but uh we are not [481:25] saving them yet. So let's save them into [481:27] a file. [481:30] Okay. So let's create a function called [481:32] save. I'm going to pass it the MAC [481:36] variable. Now what is the MAC variable? [481:38] It is storing the MAC address that this [481:42] function returns. So here I am calling [481:44] the save function and passing it the MAC [481:48] address and then this MAC address will [481:50] be saved in a file. So define save and [481:57] Mac [482:00] with open [482:03] and uh file name is going to be MAC [482:08] addresses dot txt [482:13] and uh it is going to be a append. we [482:16] are going to uh open the file in the [482:19] append mode because we want to append [482:22] each each new MAC address at the end. If [482:26] you write simply W then the new MAC [482:29] address will replace the existing MAC [482:32] address. So instead we are going to use [482:35] a it will append each new MAC address at [482:38] the end as file. [482:41] Now file [482:43] dot uh write [482:46] and write mac [482:49] plus [482:52] slash n. This is a new line character. [482:55] It will create a new line character [482:57] after appending [482:59] uh a MAC address. Right? We have already [483:02] done this in the file management [483:04] section. Right? And here this MAC [483:07] address.xt file will be created in my [483:09] current working directory which is [483:11] Python. If you want to store or create a [483:14] file in a specific location, then [483:16] specify path to it here. Okay. So let's [483:21] first verify the code if it is working [483:23] or not. [483:26] Okay. [483:28] So as you can see it has printed all the [483:30] MAC addresses. We have we are generating [483:33] 100 MAC addresses. Now let's check the [483:35] file if it has been created or not. ls. [483:38] Okay. We have the file called MAC [483:41] addresses dot MAC addresses .txt. This [483:45] is exactly what we created. And let's [483:48] get out its contents. [483:52] Notepad sorry Notepad MAC addresses.txt. [483:59] As you can see guys, inside this file we [484:01] have saved [484:04] all the 100 MAC addresses. Okay, we have [484:07] a problem here in this file. The MAC [484:11] addresses that have been saved. We have [484:15] unnecessary hyphen at the end. We need [484:19] to get rid of them. Let's see what the [484:21] problem is. Even though if you check the [484:23] output here in the output, we don't have [484:26] uh the additional hyphen. [484:30] Okay. Okay. I see the problem. Now I am [484:34] here. As you can see, I'm passing this [484:36] unformatted MAC address to the save [484:40] function. Right? So, what I'm going to [484:42] do is get rid of print. It is not [484:44] required. [484:50] MAC equal to this. [484:55] Okay. Let me remove the existing MAC [484:57] addresses. [485:02] Now this time we are not printing any [485:04] MAC address addresses. Okay, let's uh [485:08] reduce the number to 10 [485:12] and let's actually print the MAC [485:16] addresses. [485:20] Okay, we have generated 10 MAC addresses [485:23] ls. Okay, we have file here [485:27] notepad [485:30] and inside the file now we have the [485:33] exact output we wanted right okay we [485:37] have saved the MAC addresses in a clean [485:41] and uh and its correct format so let me [485:46] quickly walk you through this entire [485:48] program's flow here this loop runs 10 [485:52] times when this loop runs For the first [485:54] time I'm calling this MAC gen function. [485:58] So MAC gen function generates a MAC [486:00] address and returns that address to the [486:03] MAC gen function. After uh it receives [486:07] the value then we are assigning that [486:09] value to MAC. And here I'm formatting [486:13] the received MAC address. Right? First [486:15] I'm slicing or removing the unnecessary [486:18] hyphen from the end. Then converting [486:21] lowerase characters or letters into [486:23] uppercase. Then assigning the formatted [486:26] MAC address to MAC. And then I'm [486:28] printing the MAC address uh uh to the [486:32] output console. And at the line number [486:34] 29, I am calling the save function. [486:37] Right? I'm passing the MAC address to [486:41] the save function. I'm basically telling [486:42] my save function take this MAC address [486:45] then save it into the file when the save [486:48] function gets called. It has been [486:50] defined here. Now here I'm creating a [486:53] file called MAC addresses dot txt in the [486:56] append mode. So each new address MAC [486:59] address gets appended at the end. Now [487:02] here I'm writing the MAC address to the [487:06] file. And here we have the new line [487:08] character which will make sure that each [487:10] new address is MAC address is appended [487:13] in a new line. Okay. After finishing [487:16] this execution control returns back to [487:19] the for loop. The for loop runs for the [487:22] second time. It repeats the same thing. [487:23] Calls the max gen function. It returns a [487:27] new MAC address. Then we are formatting [487:29] that passing that value to the save [487:31] function. It saves that MAC address in a [487:34] new line. So it keeps repeating this as [487:36] long as this loop keeps running. [487:40] Okay. So let's uh increase this value to [487:43] let's say 100 and see if it saves all [487:48] the MAC addresses. And it has generated [487:50] 100 MAC addresses for sure. Let's check [487:53] the file and in this file it has saved [487:57] all the MAC addresses. So guys, that's [487:59] how you can basically put everything [488:01] together to create, you know, Python [488:03] programs. Let me know if you have any [488:06] questions. In this section, we will [488:08] explore networking using the socket [488:10] module. You will learn how to build [488:13] network applications that communicate [488:15] over the internet with servers and [488:18] remote systems. This includes [488:20] establishing server connections, [488:22] verifying network connectivity, and [488:24] developing practical tools like port [488:27] scanners. Python provides a powerful [488:29] built-in module called socket for [488:31] handling networking tasks. It is widely [488:34] used by network administrators, system [488:37] engineers, and cyber security analysts [488:40] to enable communication between systems [488:43] using standard protocols. And of course, [488:46] it is heavily used by programmers to [488:49] build network ccentric applications. In [488:51] simple terms, the socket module allows [488:53] Python programs to send and receive data [488:56] across a network. Using it, we can build [488:59] client server applications, exchange [489:02] data, and interact with network services [489:05] through protocols like TCP and UDP. It [489:09] also helps you understand key networking [489:12] concepts such as how connections are [489:14] established. Now, let's dive into the [489:17] practicals. First we need to import the [489:20] socket module. Now in the try block [489:24] we will try to try to establish a [489:27] connection with a remote host. So try [489:31] now write sock we are going to create a [489:33] socket object. Sock equal to [489:37] socket. Socket is the module of course [489:40] dot socket and socket is the function [489:44] inside the socket module. The socket [489:47] module creates a socket object. Within [489:50] the parenthesis, we need to specify two [489:53] parameters. Socket dotf [489:57] inet. [489:59] The second parameter is going to be [490:00] socket dot sock [490:04] stream. [490:06] So we have successfully created a socket [490:10] object and assigned it to the sock [490:14] variable. Now the first parameter is [490:18] this socket AFET. AFET represents the [490:22] IPv4 [490:24] address. As we already know the IP [490:26] address family has two two primary [490:30] versions. IPv4 [490:33] and IPv6. [490:35] So here I'm telling my socket function [490:37] that you are going to use the IPv4 [490:41] address to communicate with the host. [490:44] the host that we are going to provide or [490:47] specify in a minute. So, AF [490:51] Inet represents the IPv4 address. And if [490:56] you want to use IPv6 address, then you [490:59] can write in 6 like this. Now, the [491:03] socket function is going to use the IPv6 [491:06] address. However, we are going to use [491:08] the IPv4 address because it is still the [491:12] most widely used version of the IP [491:15] address family. IPv6 is relatively new. [491:19] It is not exactly new but still the IPv4 [491:23] address is the most popular and [491:25] dominant. The second parameter that we [491:28] have is this. This is called this [491:31] communication protocol. Now the [491:33] sock_stream [491:35] it represents the TCP protocol. [491:38] TCP protocol essentially makes sure that [491:42] the data is delivered to the [491:45] destination. So that's why we are using [491:47] the TCP protocol because here we are [491:49] trying to establish a connection with [491:52] the remote host. So we need a reliable [491:54] protocol that can guarantee the data [491:58] delivery. So we have configured our [492:00] socket object with these two details. [492:02] Okay, it is going to use the IPv4 [492:05] address to reach out to the server and [492:07] TCP protocol to guarantee the data [492:11] delivery. [492:13] Now using the sock variable, we can [492:18] attempt a connection with the remote [492:21] host. So dot connect. [492:26] Now the connect function accepts [492:28] parameters in the form of tupal. Tupal [492:31] is defined by parenthesis. Right? So [492:33] inside the parenthesis of connect, write [492:36] uh parenthesis [492:38] and now specify the host uh or domain [492:42] that you want to connect to. I'm going [492:44] to connect to google.com [492:46] sorry now comma and specify a port [492:51] number 443. [492:54] So here sock what is sock? Sock is a [492:58] variable which is storing this socket [493:00] object and we have configured the socket [493:03] object with these details. Right here [493:06] I'm telling my socket function that you [493:09] are going to use IP4 address and TCP [493:12] protocol. So connect function is going [493:14] to use these configurations to connect [493:17] to the specified host google.com on port [493:21] number 443. [493:24] Now connect function will uh try to [493:26] connect or establish a connection with [493:29] the google.com. [493:31] Now how does the connect function work? [493:34] What does uh it actually mean when we [493:36] say that it establishes a connection [493:39] with the google.com? Here guys, we need [493:42] to uh to understand how computers [493:46] communicate over the internet. I will [493:48] give you a very brief overview of how it [493:51] works because if I attempt to explain uh [493:55] in detail technically it will take not a [493:58] separate video rather a separate [494:01] computer networking course. I will try [494:03] to brief it so everyone can understand. [494:06] Now before you access any server on the [494:09] internet first a connection must be [494:12] established between the client and [494:15] server. Client is the system that is [494:18] trying to access the server. In in my [494:22] case, my system is client because here I [494:26] am trying to access the uh google.com or [494:29] Google's server. So, first connection [494:32] must be established between the client [494:35] and server and after a connection is [494:39] successful then we can start accessing [494:42] that server. In our case, I'm trying to [494:44] access google.com. So first before I can [494:47] access the google.com first a connection [494:51] must be established with the google.com [494:54] or Google's server to be specific only [494:56] then I will be able to search on [494:59] google.com. Now the connection is [495:02] established by something called [495:04] three-way handshake in the background. [495:09] Three-way [495:12] handshake is part of the TCP protocol [495:14] that we have specified here. In [495:17] three-way handshake, both client and [495:20] server exchange three packets between [495:24] them. In those three packets, client and [495:27] server must agree on several things or [495:31] parameters such as which security [495:34] protocol and algorithms they must use to [495:38] secure data, how much data should be [495:41] sent in each packet among other uh [495:44] details or configurations. Once both [495:48] client and server agree on all the [495:50] parameters, the connection gets [495:52] established and then we can start [495:55] accessing the google.com. Now this [495:58] three-way handshake happens [495:59] automatically in the background without [496:02] our interference. Right now once both [496:05] client and server agree on all the [496:08] parameters or configurations then the [496:11] connection get established. Now we can [496:13] start accessing the specified host which [496:16] is google.com in our case. Now [496:22] uh let me write uh [496:27] connection [496:29] successful. [496:31] So if everything goes well the connect [496:34] function is going to connect to the [496:36] google.com. Then if connection is [496:38] successful then it will uh print the [496:41] connection successful message. Now in [496:44] the accept block we are going to catch [496:46] the errors. So except socket dot error. [496:51] The socket dot error exception is going [496:54] to catch the error. If the connect [496:57] function for some reasons is not able to [497:00] connect to the host then it will raise a [497:03] runtime error that we are catching here [497:06] in the accept block [497:09] print [497:12] could not connect. Now the obvious [497:16] question here is when a connection will [497:20] not be a success or when connection [497:23] can't be established. Well, there are [497:26] many reasons. For example, if the host [497:29] name that you specify here, if the host [497:31] is down or not available, then connect [497:35] function will not be able to establish a [497:37] connection, then the control will [497:40] immediately move to the the accept [497:43] block. Or if the port number that we [497:47] have specified here is either filtered [497:50] by a firewall or closed then also the [497:53] connect function will not be able to [497:55] establish the connection to the host and [497:58] the accept block will be executed or if [498:02] your internet connection is not working [498:04] then the connect function will not be [498:07] able to establish a connection with the [498:09] host and the accept block will be [498:12] executed. So except block catches all [498:15] types of runtime errors. So let's [498:18] execute the code and see what we get. As [498:21] you can see guys, connection successful [498:24] because google.com is it is up and [498:26] running and port number that we have [498:29] specified is 443. [498:32] The 443 is the default port for HTTPS or [498:36] secure websites. That's why we have [498:38] specified the port number 443. So [498:40] connection was successful. Once the [498:44] connect function uh establishes a [498:46] connection successfully then Python [498:49] prints all the lines that we have [498:51] written in the try block. It will [498:53] execute everything that you write after [498:55] the connect function. Here we have [498:57] written this print statement. Right? [499:00] Now what happens if I specify another [499:03] port let's say 21. Now 21 port number is [499:06] typically closed. In such case, the [499:09] connect function will not be able to [499:12] establish a connection with Google [499:14] successfully because port number 21 is [499:16] closed. [499:18] So let's run the code. [499:23] As you can see guys, it is taking much [499:25] longer than the previous [499:27] execution because the connect function [499:30] is trying to reconnect on the port [499:33] number 21. As you can see could not [499:35] connect because port number 21 is [499:37] closed. Therefore, it could not uh [499:40] establish establish connection with the [499:44] google.com on this specific port. So, we [499:47] have the message could not connect the [499:49] accept block was executed. [499:56] Now, one thing that we can do to [499:58] optimize our code is set the time out. [500:02] So, sock dot [500:05] set [500:08] timeout [500:10] specify the seconds let's say two. [500:13] Now, what does this set timeout does? [500:16] Well, the way it works is if the connect [500:20] function is not able to establish [500:23] connection with the specified host [500:25] within the 2 seconds or whatever number [500:28] you specify then it will move on. It [500:32] will execute the accept block. The way [500:35] the connect function by default works is [500:38] if in the first attempt it is not able [500:40] to establish connection then it will [500:44] reconnect. it will try to reconnect. It [500:47] does it for several times which is which [500:49] can be problematic because it can freeze [500:51] your program or make it slow. But here [500:55] I'm telling my program that you are only [500:58] going to attempt connection for 2 [501:00] seconds. If you connect within 2 seconds [501:03] then it is good. If not then we will [501:05] move on. The accept block will be [501:08] executed. So let's uh rerun this time. [501:14] As you can see this time our program was [501:17] executed quickly. So connect function [501:20] only attempted to connect for 2 seconds [501:23] and within 2 seconds it was not able to [501:26] establish the connection. So accept [501:28] block was executed. Now let me comment [501:31] this out and execute it again without [501:34] the set timeout. As you can see, it is [501:36] going to take a much longer to to [501:40] execute because connect function is [501:42] trying to reconnect to the google.com on [501:45] port number 21. It is attempting [501:48] multiple connections which is leaving [501:50] our program hanging as you can see which [501:52] is very problematic for most real world [501:55] applications as you can see. But with [501:57] the set timeout, we can actually tell [502:00] connect function for how long it should [502:04] try to connect. So yeah, that's how the [502:07] set timeout function works. Now guys, [502:09] never forget to close the connection in [502:11] the finally block. So soft dot [502:15] close. [502:17] So close function is going to close the [502:21] network resources after a connection is [502:24] successful. So it is a recommended [502:27] practice. Okay. Make sure to spell the [502:30] finally correctly. Doublel. [502:34] It will not have any visible impact in [502:37] our output. But in the background it [502:39] will close the the network resources [502:41] being allocated to the connection once [502:45] the connection completes. And I almost [502:48] forgot that here I have used sock.stream [502:51] which represents the TCP protocol. We [502:54] can also use UDP protocol. UDP protocol [502:58] is uh uh is represented by sock [503:03] sock [503:05] DG RAM. [503:07] However, the UDP protocol is used for [503:10] very specific applications. For example, [503:12] if you are building a real real-time [503:15] applications like uh a chat system or [503:18] live streaming, in such cases, we use [503:20] the UDP protocol. For 95% applications, [503:24] we use the [503:26] we use the TCP protocol which is [503:30] represented by sock_stream [503:32] because TCP protocol is a reliable [503:34] protocol which guarantees the data [503:37] delivery. Here since we are trying to [503:40] establish a connection with google.com, [503:43] we need a reliable protocol that can [503:45] guarantee the uh data delivery. This is [503:49] exactly what the TCP protocol does. [503:53] Let me know guys if you have any [503:54] questions. In this video, we will dive [503:57] deeper into the socket module. [503:59] Specifically, we will learn about the [504:01] get host by name function. Get host by [504:03] name performs DNS resolution. It takes a [504:07] domain name and returns its [504:09] corresponding IPv4 address. Every [504:11] website or domain such as Google or [504:14] Facebook has at least one IP address [504:17] assigned to it. For example, when you [504:18] type google.com into a web browser, a [504:22] protocol called DNS translates that [504:25] domain name into its IP address. Your [504:28] system then communicates with Google [504:31] using that specific IP address. These [504:34] domain names exist only for human [504:37] convenience. Computers actually [504:39] communicate using the IP addresses. [504:42] There are many tools available that [504:44] allow us to quickly find or retrieve IP [504:48] address of any website. Now in the [504:50] Python socket module has the get host by [504:53] name function which allows us to [504:55] retrieve the IPv4 address of any website [504:59] easily. Now let's dive into the [505:01] practicals. [505:04] So in the try block we will attempt to [505:07] retrieve IP address of a domain name [505:12] IP equal to socket dot [505:16] get [505:18] host [505:20] by name [505:23] within the parenthesis specify the [505:26] domain name whose IP address you want to [505:29] retrieve. I want to retrieve IP address [505:31] of Google. So get host uh by name [505:34] function needs one parameter. You have [505:37] to tell it the domain name or the [505:40] website's name whose IP address you want [505:42] to retrieve. So after it uh retrieves [505:46] the IP address, then uh it is going to [505:48] assign that IP address to the variable [505:51] IP. [505:54] So print [505:56] let's print IP. Now in the accept block [505:59] we are going to catch the error if it [506:01] raises any errors. Except [506:04] socket dot G ai [506:09] error. G AI stands for get address [506:13] information and if it is not able to [506:16] retrieve the IP address of the specified [506:19] host then that error will be caught in [506:22] the accept block. Uh we are going to [506:24] print uh the error message. [506:28] Please provide [506:31] a [506:33] valid [506:34] domain name. [506:39] Let's execute the code. [506:41] As you can see guys, we have [506:43] successfully retrieved the IP address of [506:46] the specified host google.com. This is [506:49] the IP address of google.com. So what [506:52] I'm going to do is uh copy this IP [506:54] address and paste it in uh in browser. [506:59] Let me paste it here. Press enter. As [507:02] you can see guys, it has automatically [507:04] redirected me to the google.com because [507:06] this is the IP address of the the [507:09] google.com. Similarly, this way you can [507:12] uh retrieve uh IPv4 address of any [507:17] website or domain name on [507:21] uh on internet [507:23] yahoo.com. [507:25] This is the IP address of yahoo.com. [507:28] Right now, what happens if you specify [507:32] an invalid domain name like this? [507:36] This time it will raise an error. Let me [507:39] execute the code. As you can see, please [507:41] provide a valid domain name. So, what is [507:44] happening here? See guys, every website [507:47] or domain name on the internet has at [507:51] least one IP address assigned to it. So, [507:54] here I have provided an invalid domain [507:58] name. Since this uh domain or website [508:01] doesn't exist on the internet, the get [508:03] host by name function was not able to [508:06] retrieve its IP address. Since it was [508:09] not able to retrieve its IP address, it [508:12] raised a runtime error. That error was [508:15] called here in the accept block. So [508:18] guys, that's how it actually works. I [508:20] hope guys it is clear. Now let's [508:23] retrieve IP address of x.com former [508:26] formerly known as Google. uh sorry [508:29] Twitter as you can see this is the IP [508:31] address of x.com now guys this is going [508:34] to be very important uh later in our [508:37] project that we will build later here we [508:40] are basically validating a valid domain [508:44] name right to validate a domain name in [508:47] a Python program it is simple we use the [508:50] get host by a name function right it [508:54] will retrieve the IP address of a domain [508:59] name if that domain name uh exists on [509:02] the internet but if you provide a domain [509:04] name that doesn't exist then it won't be [509:06] able to retrieve IP address of that [509:08] domain name and raise an error now in [509:11] the background this get host by name [509:14] function uses something called the DNS [509:17] DNS protocol is responsible for [509:21] resolving a domain name to its [509:23] corresponding IP address. So in the [509:25] background it is the DNS protocol that [509:28] actually fetches the IP address of the [509:31] provided host. Then we are assigning [509:34] that to to the IP variable. So guys if [509:38] you want to learn about you know the [509:40] protocols that I'm discussing in this uh [509:42] uh in this section like TCP, UDP or DNS [509:46] then I have covered all of them in my [509:48] cyber security course uh using [509:51] animations. Okay. Okay. So, feel free to [509:53] check that out if you are new to [509:56] computer networking. And of course, you [509:57] don't you don't need to enroll in my [510:00] course. You can use any any other [510:02] resources or courses on Udemy or other [510:05] platforms because computer networking is [510:08] a must for especially for networking [510:11] engineers, uh, cyber security analysts, [510:14] cloud engineers or even for programmers [510:17] in general. So, thank you very much [510:19] guys. In this video, we are going to [510:21] check our internet connectivity to [510:23] determine if we are online or offline. [510:28] Now, let's dive into the practicals and [510:31] the program is going to remain almost uh [510:34] the same uh as we did in the previous [510:37] video with the with minor modifications. [510:40] So, first of course we need to import [510:41] the socket in the drive block. we will [510:44] attempt to establish a connection with [510:47] uh a reliable host like Google. So let's [510:50] create a socket object. So socket dot [510:54] socket function [510:57] socket dot [511:01] af_inet [511:03] comma socket dot sock [511:09] stream we are going to use the TCP [511:13] protocol to make a connection and here [511:16] I'm using IPB version 4 uh to create a [511:19] connection with the host and [511:23] sock dot connect [511:26] now parenthesis again because as we [511:30] already know the connect function [511:31] accepts parameters as the tupal. So I'm [511:35] going to connect to google.com [511:39] on port number 443. So when you create [511:42] an application that checks internet [511:44] connectivity, [511:45] make sure to specify a reliable host or [511:49] the remote host name that is always up [511:52] and running just like Google because [511:54] Google is almost always you know up and [511:57] running. It is never down. [512:00] So if connection is successful [512:03] then we are going to write the message [512:05] you are online [512:10] and uh let's define the accept block [512:14] socket dot error [512:19] print you are offline [512:25] you are offline [512:27] and of course finally also needs to be [512:31] defined. Even though finally is optional [512:34] but it is mandatory when it comes to the [512:37] program optimization. [512:40] We need to close the [512:45] network connection [512:47] sock.lo. [512:48] So what is happening here? As we already [512:50] know if the connect function [512:53] successfully connects to the specified [512:55] host then connection is a successor. [512:59] However, if connect function is not able [513:01] to establish connection uh with the [513:04] specified host, then it raises an error. [513:08] There are several reasons that connect [513:10] function may not be able to successfully [513:13] connect uh with the specified host, [513:16] right? such as uh uh the host name that [513:19] you provide here is not up and running [513:21] or the port number that you specify here [513:24] is either filtered by a firewall or [513:27] closed or the most importantly if your [513:31] internet connection is not working or if [513:33] you are offline then also connect [513:36] function will not be able to establish [513:39] connection with the host because it is [513:42] pretty obvious right in order to [513:43] communicate with the devices on the [513:45] internet you need to have a working [513:48] internet connection. So if your internet [513:50] connection is not working, connect [513:52] function will not be able to reach out [513:54] to the host and it will raise an error [513:58] then that error will be caught in the [514:00] accept block. So we are writing this [514:02] message. For example, let's uh uh run [514:04] the code. Uh okay. Okay. We have an [514:07] error here. During handling the above [514:10] exception, another occurred module [514:13] socket has no Okay. So we have the [514:15] attribute error module socket has no [514:18] okay looks like there is a spelling [514:21] mistake [514:23] at line number four. [514:25] Okay, socket it is socket. Sorry guys, [514:29] socket. [514:31] And of course, guys, we need to set the [514:35] time out. Sock dot set [514:41] timeout [514:44] for 3 seconds. So if connect function is [514:47] not able to uh establish connection [514:50] within 3 seconds then we will exit out [514:53] of the try block and accept block will [514:56] be executed and you are online. As you [514:59] can see the connection was uh made [515:02] almost immediately. [515:05] Now what I'm going to do is uh [515:10] uh disconnect or discontinue my internet [515:13] connection. Let me disconnect and [515:16] let's uh run the code. As you can see [515:19] guys, you are offline, right? We got the [515:23] the output immediately. So what I would [515:26] like to do is delay the output a little [515:29] probably by a second because this way it [515:31] looks almost you know it doesn't look uh [515:34] that user friendly as you can see. Okay. [515:36] So, what I'm going to do is import [515:40] time. And here [515:46] time dot sleep [515:50] by [515:52] 1 second. [515:54] As you can see now we have a delay of 1 [515:56] second. Then we get this message you are [516:00] offline. So when the execution goes [516:03] inside the accept block first we are [516:06] using the time dots sleep method right [516:09] it will delay your execution for 1 [516:11] second after 1 second it will print the [516:14] message you are offline so that's how [516:17] you can check your internet connection [516:19] okay like I said earlier the program is [516:21] pretty much same as we did in the first [516:23] video the only thing that you need to be [516:27] careful about when checking internet [516:29] connectivity is specifying a reliable [516:31] host that is 24/7 up and running that is [516:34] google.com or or similar website. So now [516:37] let me [516:41] uh connect to the internet and uh [516:45] re-execute the code. [516:49] As you can see you are online now. It is [516:51] working as it