WEBVTT

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Game Basics
Installing Visual Studio and Intro to Programming

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Hello everyone

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I'm Lee Yeong-hoon, and I'm in charge
of this C#-based object-oriented programming lecture

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The course will cover

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installing Visual Studio and programming basics,

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data types and variables,

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conditional statements and loops,

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and functions and classes,

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in that order

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In this lesson, we will

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install Visual Studio, an integrated development environment,

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learn basic programming concepts,

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and study C# fundamentals

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Installing Visual Studio
Printing Hello World

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Today, we will install Visual Studio,

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try simple coding,

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and also discuss the overall

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development process

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Let's install Visual Studio from Google

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Let's search

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Visual Studio

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There's version 2022,

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so you can use this version

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Even for Unity,

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we're using their version 2022

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So here, we see many things

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And we have Community 2022

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This is the free version

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So let's use this

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Over to this side,

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we're seeing some downloads

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All done

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If it doesn't work, click here

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Select Visual Studio Setup

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Now we can install through

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Visual Studio Installer

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So let's continue installing

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This may take a while

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based on your internet speed

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Let's wait a bit and continue

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To install Visual Studio,

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this Installer works like a launcher

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Sao this has expansions

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that we can add to Visual Studio

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for our programming

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Before we begin,

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we need to check

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this .NET Desktop Programming

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And down here,

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you'll see Game Development with Unity

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Let's check this as well

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So again, check for .Net Desktop

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and also this Game Development

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Check for these two

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Here, we also have C++

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If you're using Unreal,

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you can also check this

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Next, to bottom right,

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click Install

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This will download

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all the necessary information

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Now that this is done,

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it will automatically open

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We had this box ticked,

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so that it opens right away

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So now we have this

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Create an account and log in

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Then this will continue to be free

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It's also free for the first month, with the trial version

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For now, I will skip

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and continue

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So you can select

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the theme that you like

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I will keep the dark mode

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Now, for the Visual Studio,

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first, through the Visual Studio Installer,

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Click on M for Modify

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This allows us to add more features,

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or remove any

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You can untick the box

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to remove it

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That's how you manage these

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Now that we no longer need the Installer,

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I’ll go ahead and close it

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Once that’s done, Visual Studio should open like this

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You can see various options here

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We’re going to create a new project,

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so let’s click on that

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ou’ll see a variety of templates,

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but we won’t use all of them

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Here, you’ll find the language options

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We’ll select C#

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Next, on the far right, you’ll see a format option

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We’ll use the Console app

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After selecting Console,

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two options will appear

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We’ll choose .NET Framework

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Once that’s selected,

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click the Next button

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Now, we can configure our new project

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This window shows

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the project

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and solution names

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It’s important to understand

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what a solution

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and a project are

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A solution is a broader concept,

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and a project is

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part of the solution

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So basically,

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if you’re only making one project,

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you can use the same name

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for both the solution and the project

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But if you’re managing multiple projects

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under one solution,

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you can give them different names

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Let’s create a project

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to print Hello World

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When people first learn coding,

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printing Hello World

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is usually the first thing they do

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If you can do that, you’re already halfway there!

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Let’s create a project

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to print Hello World

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For the solution name,

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I’ll use Coding

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That's it

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Now, for the location

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We’re talking about

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where to save this project and solution

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You can leave it as it is,

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but I’ll go ahead and put it in a new folder

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You’ll see

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that I’ve created a folder called Project,

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so I’ll save it there

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After setting that,

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click the Create button

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You’ll see

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the project being created

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If you open the folder,

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You’ll find that

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a Hello World project folder

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is created under

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the Coding folder

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There’s also a file named Coding.sln

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This is the solution file

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So here is the solution file,

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and the Hello World project under it

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That's how it works

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Now that we understand the structure,

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let’s open the Visual Studio project

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Here,

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you should see the Solution Explorer

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If you don’t see it,

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go to the top bar and click

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on Window Layout Reset

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Click on it,

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and you'll see it

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Now, in the Solution Explorer,

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you’ll see “Coding” as the solution,

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and below that,

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the Hello World project

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The file we’re working

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with now is called Program.cs

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Let’s go ahead and print Hello World

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I know we’re still beginners, but here’s what we do

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You’ll see the word Main

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This is the function we’ll use

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At Main, we have the curly braces

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Inside the curly braces

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is called the scope

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I’ll call it a space for now,

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because it occupies a space like so

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You’ll see these scopes here as well

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Inside this scope under Main,

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you can automatically indent

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by pressing the Tab key

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Now, type this

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Console

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And a period

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It will complete it for you

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WriteLine

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Press Tab to get this

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And open a parenthesis

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And add quotation marks

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Let's type Hello World

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There we have it

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Let's save it

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To save, use Ctrl+S

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For saving all files,

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you can use Ctrl+Shift+S

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Both Ctrl+S and Ctrl+Shift+S

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can save the file

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This is our source file,

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or a source code

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This is where we write our codes

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Let's run it

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After saving,

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look at the top for the button

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Or if you look here, there is an option

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called Build and Debug

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When you build, you make the program ready to run

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The build process

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turns your source code

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into an executable file

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So, let’s try this

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Let's try building it now

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Click on Build, and the process will start

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It's building

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The build is complete,

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and you’ll see a message saying, Build 1 succeeded

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Then, there’s the Debug section

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You’ll find options

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to either to start debugging

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or to start without debugging

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You can use the shortcuts F5

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or Ctrl+F5 to do these

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It's the same thing here

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This will start the program with debugging enabled

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Let’s try running it with this

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Here’s what happens

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when you press Ctrl+F5

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A black console window will open up

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This window is called the console window

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In the console, you should see

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Hello World displayed

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Now, let’s close the console window

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This is how the structure is set up

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In the code, there is a line that says using,

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which means we are using

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some system functionality

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There’s also the term namespace,

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which has name and space in its term, right?

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It stands for creating a container or space for code

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Let me explicate

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Inside the namespace,

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you will see the class Program

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Hover over Program to see its details

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Here at class,

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the Program class is the only class here,

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but in the upper part of the screen, you’ll notice

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HelloWorld.Program written

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So the meaning of this namespace

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is that it holds a space,

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and its keywords

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that belong to that space

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are part of the namespace

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Now, let’s take a closer look

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The Main function,

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which we referred to earlier,

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is where the program begins

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The Main function is known as the entry point

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of the C# application

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Let me explain about application

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Have you heard about app?

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App stands for application

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We're familiar with app

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An application is referring

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to a software application

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When we create a program and run it,

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it begins to execute

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in a running process

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So, when you run the program,

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it's the first function that gets called

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That's how you can understand it

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That’s why it’s referred to as the entry point

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In C#, there is exactly one entry point

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So, here, the Main function

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serves as the entry point

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If we look at the details,

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you’ll see the word static,

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followed by void Main,

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Here you’ll also see the word string,

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which means a string, or text

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String

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And this means it’s an array

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And args

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represents parameters

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If you hover over it, you’ll see it says parameters

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We’ll dive deeper into functions later,

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when we get a chance,

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but for now, let’s test it briefly

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As you can see, there is the args variable

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We’ll differentiate between
when args exists and when it doesn’t

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We will output different results based on that

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So here, I’ll write

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something like this

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If there is a value in args,

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00:13:51.619 --> 00:13:54.113
I will process it accordingly

290
00:13:54.113 --> 00:13:56.524
To check whether there is a value or not,

291
00:13:56.524 --> 00:13:58.717
some consideration is required, right?

292
00:13:58.717 --> 00:14:01.299
That there is a value means this

293
00:14:01.299 --> 00:14:04.988
To check if a value exists in args,

294
00:14:04.988 --> 00:14:08.046
we check if its length is greater than 0

295
00:14:08.046 --> 00:14:09.157
If it is, I will express it this way

296
00:14:09.157 --> 00:14:15.084
If there is a value and the length is greater than 0…

297
00:14:15.084 --> 00:14:18.798
This will indicate that there is a value

298
00:14:18.798 --> 00:14:23.087
If the value exists, we will output

299
00:14:23.087 --> 00:14:24.087
the value from args

300
00:14:24.087 --> 00:14:25.607
Otherwise, we will output

301
00:14:25.607 --> 00:14:27.099
Hello World

302
00:14:27.099 --> 00:14:33.267
So if there is a value,

303
00:14:35.460 --> 00:14:37.370
I want to output the first value in args

304
00:14:37.370 --> 00:14:40.270
Actually, in programming,

305
00:14:40.270 --> 00:14:43.219
we often talk about input and output

306
00:14:43.219 --> 00:14:45.720
Right now, this is written as Write,

307
00:14:45.720 --> 00:14:49.031
Console.Write, which means output

308
00:14:49.031 --> 00:14:51.034
But there is also input

309
00:14:51.034 --> 00:14:54.442
In the console, there is Read

310
00:14:54.442 --> 00:14:56.468
There is Read,

311
00:14:56.468 --> 00:14:59.539
ReadKey, and ReadLine

312
00:14:59.539 --> 00:15:00.871
By using these,

313
00:15:00.871 --> 00:15:03.484
we can read the data

314
00:15:03.484 --> 00:15:05.430
entered from the keyboard

315
00:15:05.430 --> 00:15:08.619
Just remember this for now

316
00:15:08.619 --> 00:15:11.891
For now, we’ll focus on output only

317
00:15:11.891 --> 00:15:15.098
So let’s output it here

318
00:15:15.098 --> 00:15:16.282
If that's not the case,

319
00:15:17.639 --> 00:15:21.066
or if there is no value in args,

320
00:15:21.066 --> 00:15:25.930
we’ll output Hello World

321
00:15:25.930 --> 00:15:27.667
Let’s do this now

322
00:15:27.667 --> 00:15:30.011
This will be covered later,

323
00:15:30.011 --> 00:15:32.762
when we learn about conditionals

324
00:15:32.762 --> 00:15:35.235
But for now, let’s keep it simple

325
00:15:35.235 --> 00:15:36.617
and try it out

326
00:15:36.617 --> 00:15:38.565
If you write if here,

327
00:15:38.565 --> 00:15:40.335
it will automatically

328
00:15:40.335 --> 00:15:42.390
generate the code for you

329
00:15:42.390 --> 00:15:43.678
Let's write it like that

330
00:15:46.820 --> 00:15:50.356
You add a condition here,

331
00:15:50.356 --> 00:15:55.178
and this is for comparison

332
00:15:55.178 --> 00:15:58.300
So these two equal signs mean equal to

333
00:15:58.300 --> 00:16:00.902
It checks if it equals 0

334
00:16:00.902 --> 00:16:03.879
But what I want is, If it’s greater than 0

335
00:16:03.879 --> 00:16:08.170
So you can write this for that

336
00:16:08.170 --> 00:16:11.253
Now let’s proceed with this

337
00:16:11.253 --> 00:16:14.820
If you hold the Alt key and press the arrow keys,

338
00:16:14.820 --> 00:16:19.387
the line with the cursor here

339
00:16:19.387 --> 00:16:21.579
moves like so

340
00:16:21.579 --> 00:16:23.235
You can also group this together

341
00:16:23.235 --> 00:16:25.248
So, press the shift key

342
00:16:25.248 --> 00:16:27.321
and select the block like this,

343
00:16:27.321 --> 00:16:30.136
then press the alt key and move it up and down

344
00:16:30.136 --> 00:16:31.940
It will move together

345
00:16:31.940 --> 00:16:33.199
Using these,

346
00:16:33.199 --> 00:16:36.045
it would be great to code faster

347
00:16:36.055 --> 00:16:38.219
I will press the alt key and move this up

348
00:16:38.219 --> 00:16:39.957
And if not, then this will be

349
00:16:39.957 --> 00:16:43.181
called else

350
00:16:43.181 --> 00:16:45.318
You can write it like this

351
00:16:48.396 --> 00:16:51.040
Let’s try to output this

352
00:16:51.040 --> 00:16:54.738
Here, we will use Console.WriteLine as it is

353
00:17:00.870 --> 00:17:04.139
This is the first value of args

354
00:17:04.139 --> 00:17:05.327
You can write it like this

355
00:17:05.327 --> 00:17:09.278
The first value in an array starts from 0

356
00:17:09.278 --> 00:17:10.614
Since we haven’t

357
00:17:10.614 --> 00:17:13.074
learned things like arrays yet,

358
00:17:13.074 --> 00:17:16.070
you might not understand it well, but let’s try it out

359
00:17:16.070 --> 00:17:18.419
So, this array actually

360
00:17:18.419 --> 00:17:19.912
refers to a list

361
00:17:19.912 --> 00:17:23.857
It means the first item in the list

362
00:17:25.758 --> 00:17:29.935
In computer programming,

363
00:17:29.935 --> 00:17:33.569
we start counting from 0

364
00:17:33.569 --> 00:17:37.430
This is called zero-based indexing

365
00:17:37.430 --> 00:17:38.835
So when it says 0,

366
00:17:38.835 --> 00:17:43.488
it means it starts from 0

367
00:17:43.488 --> 00:17:45.469
Therefore, the length is greater than 0

368
00:17:45.469 --> 00:17:48.887
If there’s one, it would be 1

369
00:17:48.887 --> 00:17:51.455
The first item is 0

370
00:17:51.455 --> 00:17:53.780
You can think of it like that

371
00:17:53.780 --> 00:17:55.497
Let's save this

372
00:17:55.497 --> 00:17:59.048
and try running it

373
00:17:59.048 --> 00:18:02.670
Then, of course, Hello World will be printed

374
00:18:02.670 --> 00:18:05.061
This is because,

375
00:18:05.061 --> 00:18:07.580
when we start this program,

376
00:18:07.580 --> 00:18:10.255
since no parameters were given,

377
00:18:10.255 --> 00:18:11.819
It will show this

378
00:18:11.819 --> 00:18:13.995
Now, to test this,

379
00:18:13.995 --> 00:18:18.022
We should check the generated executable, right?

380
00:18:18.022 --> 00:18:21.717
The current folder is here

381
00:18:21.717 --> 00:18:23.726
When you go to this folder, you’ll see the program

382
00:18:23.726 --> 00:18:25.914
To this open file,

383
00:18:25.914 --> 00:18:29.021
right-click the open file,

384
00:18:29.021 --> 00:18:31.619
and you’ll see an option to Open Parent Folder

385
00:18:31.619 --> 00:18:34.675
Click this to go there

386
00:18:34.675 --> 00:18:37.014
Right behind here,

387
00:18:37.014 --> 00:18:41.179
you can enter the Hello World folder and look

388
00:18:41.179 --> 00:18:44.225
There’s a folder called bin

389
00:18:44.225 --> 00:18:46.176
This stands for binary

390
00:18:46.176 --> 00:18:47.901
Inside the bin folder,

391
00:18:47.901 --> 00:18:48.953
you’ll see a Debug folder

392
00:18:48.953 --> 00:18:50.974
It's Debug because of this

393
00:18:50.974 --> 00:18:53.445
It says Debug here

394
00:18:53.445 --> 00:18:58.060
If you change it to Release and build,

395
00:18:58.060 --> 00:19:01.688
like this, build,

396
00:19:01.688 --> 00:19:05.325
a Release folder will also be created

397
00:19:07.266 --> 00:19:10.855
But I will keep it as Debug

398
00:19:10.855 --> 00:19:16.300
Debug is selected, and the build shortcut is Ctrl+B

399
00:19:16.300 --> 00:19:19.097
So, you can press Ctrl+B

400
00:19:19.097 --> 00:19:21.439
This will build the project

401
00:19:26.043 --> 00:19:27.266
It seems a bit strange

402
00:19:27.266 --> 00:19:28.054
Let’s do it like this

403
00:19:30.024 --> 00:19:32.827
So we will build like this

404
00:19:32.827 --> 00:19:34.438
Let’s delete everything and try again

405
00:19:37.766 --> 00:19:40.315
When you build, the file will be created again

406
00:19:40.315 --> 00:19:41.738
Here it is

407
00:19:41.738 --> 00:19:45.372
Now, let’s look

408
00:19:45.372 --> 00:19:47.223
at the file extension

409
00:19:47.223 --> 00:19:49.917
You’ll see that it creates an exe file

410
00:19:49.917 --> 00:19:53.300
If you double-click it,

411
00:19:53.300 --> 00:19:55.059
Hello World should be printed

412
00:19:55.059 --> 00:19:57.136
But it happens too quickly

413
00:19:57.136 --> 00:19:58.846
for us to see anything

414
00:19:58.846 --> 00:20:00.496
If you right-click here,

415
00:20:00.496 --> 00:20:02.533
I have an option called Open Terminal

416
00:20:02.533 --> 00:20:04.303
Some of you might not see this,

417
00:20:04.303 --> 00:20:06.139
that could be the case

418
00:20:06.139 --> 00:20:07.353
So let me show you how

419
00:20:07.353 --> 00:20:11.459
Here, you’ll see a search button, right?

420
00:20:11.459 --> 00:20:15.227
Type cmd
You’ll find something called Command Prompt

421
00:20:15.227 --> 00:20:17.531
This is also called a console

422
00:20:17.531 --> 00:20:20.660
Click it to open the window

423
00:20:20.660 --> 00:20:24.221
You’ll see that black window we saw earlier, right?

424
00:20:24.221 --> 00:20:28.019
Next, we are going to move to this folder

425
00:20:28.019 --> 00:20:30.344
Click here at the top

426
00:20:30.344 --> 00:20:35.739
This will give you the full absolute path of this folder

427
00:20:35.739 --> 00:20:38.239
I’ll copy this

428
00:20:38.239 --> 00:20:40.281
Now, copy it

429
00:20:40.281 --> 00:20:44.798
Then, go back to the console

430
00:20:44.798 --> 00:20:46.928
There’s a command called Change Directory,

431
00:20:46.928 --> 00:20:48.690
which is cd

432
00:20:48.690 --> 00:20:49.791
Change Directory

433
00:20:49.791 --> 00:20:53.246
In programming, we often refer to folders as directories

434
00:20:53.246 --> 00:20:55.464
We’ll move to this directory

435
00:20:55.464 --> 00:20:58.344
So, type Change Directory, then leave a space,

436
00:20:58.344 --> 00:21:01.339
Then paste the part we just copied

437
00:21:01.339 --> 00:21:04.705
Right-click to paste what we have

438
00:21:04.705 --> 00:21:06.886
Now it pastes in

439
00:21:06.886 --> 00:21:09.250
Now press Enter

440
00:21:09.250 --> 00:21:12.233
You’ll see the directory has been changed

441
00:21:12.233 --> 00:21:15.900
We are going to run Hello World.exe from here

442
00:21:15.900 --> 00:21:17.930
Just type Hello World

443
00:21:17.930 --> 00:21:20.860
Instead of typing it all out, type the beginning

444
00:21:20.860 --> 00:21:22.638
Then press the tab key

445
00:21:22.638 --> 00:21:24.425
It will auto-complete

446
00:21:25.900 --> 00:21:27.304
If you press tab several times,

447
00:21:27.304 --> 00:21:30.949
The files with the same name

448
00:21:30.949 --> 00:21:34.664
in the folder will cycle through

449
00:21:34.664 --> 00:21:35.857
Select this one

450
00:21:37.778 --> 00:21:39.400
I will select this

451
00:21:39.400 --> 00:21:41.549
Use it and press Enter

452
00:21:41.549 --> 00:21:43.540
Hello World will be printed

453
00:21:43.540 --> 00:21:45.689
If you want

454
00:21:45.689 --> 00:21:47.302
to rewrite the previous code,

455
00:21:48.916 --> 00:21:50.603
just press the up arrow

456
00:21:50.603 --> 00:21:53.678
It will bring up the last thing you wrote

457
00:21:53.678 --> 00:21:55.969
Then leave a space

458
00:21:55.969 --> 00:21:58.638
Let’s try writing 1, 2, 3, 4

459
00:22:00.420 --> 00:22:02.070
Now press Enter

460
00:22:02.070 --> 00:22:05.980
This time, 1, 2, 3, 4 will be printed

461
00:22:05.980 --> 00:22:07.859
What this means is

462
00:22:07.859 --> 00:22:10.153
when you have an executable file like this,

463
00:22:10.153 --> 00:22:11.743
if you add a space

464
00:22:11.743 --> 00:22:13.993
after the executable file,

465
00:22:13.993 --> 00:22:18.799
it will be stored as a parameter

466
00:22:18.799 --> 00:22:20.404
So the parameter

467
00:22:20.404 --> 00:22:22.859
becomes available now

468
00:22:22.859 --> 00:22:24.805
Then we can

469
00:22:24.805 --> 00:22:28.009
print that value

470
00:22:30.979 --> 00:22:32.248
It’s simple, right?

471
00:22:32.248 --> 00:22:34.610
This is the structure

472
00:22:34.610 --> 00:22:37.636
In this way,

473
00:22:37.636 --> 00:22:40.082
we can create this program

474
00:22:40.082 --> 00:22:42.682
Again, there is the concept of Debug

475
00:22:42.682 --> 00:22:45.300
or Release

476
00:22:45.300 --> 00:22:48.850
Debug is for debugging

477
00:22:48.850 --> 00:22:53.479
It creates an executable file

478
00:22:53.479 --> 00:22:54.975
that helps find bugs

479
00:22:54.975 --> 00:22:58.383
Release is different

480
00:22:58.383 --> 00:23:01.579
it strips everything out for later release or packaging

481
00:23:01.579 --> 00:23:02.782
If you want to distribute it to others,

482
00:23:02.782 --> 00:23:05.266
usually, you set it to Release,

483
00:23:05.266 --> 00:23:06.055
then create it

484
00:23:06.055 --> 00:23:09.631
So, with both Release and Debug,

485
00:23:09.631 --> 00:23:13.213
you can create the same executable file

486
00:23:13.213 --> 00:23:15.359
To recap, this process

487
00:23:15.359 --> 00:23:16.798
is called the build process

488
00:23:17.434 --> 00:23:21.068
Basic Concepts of Programming
and the C# Compiler Execution

489
00:23:21.269 --> 00:23:25.527
To clarify the term build,

490
00:23:33.998 --> 00:23:35.699
the build, like this

491
00:23:35.699 --> 00:23:38.461
The build process is this

492
00:23:38.461 --> 00:23:41.500
The source file, the C# code

493
00:23:41.500 --> 00:23:43.256
It's a code

494
00:23:43.256 --> 00:23:44.686
Let's say a code

495
00:23:46.289 --> 00:23:47.709
So this C# code

496
00:23:49.927 --> 00:23:51.070
It turns into an executable file

497
00:23:55.968 --> 00:23:58.109
The process of turning that code into a file

498
00:23:58.109 --> 00:24:00.754
is called build

499
00:24:00.754 --> 00:24:02.178
Then, when this code is

500
00:24:02.178 --> 00:24:04.962
made into an executable file,

501
00:24:04.962 --> 00:24:07.210
The action of making this happen

502
00:24:07.210 --> 00:24:08.398
is called compiling

503
00:24:11.339 --> 00:24:13.565
Yes, this is the structure

504
00:24:13.565 --> 00:24:17.397
I’ll explain this again later

505
00:24:17.397 --> 00:24:19.868
But roughly, this is how it looks

506
00:24:19.868 --> 00:24:21.991
The file that’s created

507
00:24:21.991 --> 00:24:24.699
will be here, as you see

508
00:24:24.699 --> 00:24:27.268
If you look, the Debug file is

509
00:24:27.268 --> 00:24:29.596
about 5KB

510
00:24:29.596 --> 00:24:31.579
Then, as for Release

511
00:24:31.579 --> 00:24:34.094
Ah, it’s the same, 5KB

512
00:24:34.094 --> 00:24:35.737
So, this is how it gets created

513
00:24:39.252 --> 00:24:42.579
Maybe because we haven’t written much,

514
00:24:42.579 --> 00:24:44.849
The size difference is almost nonexistent

515
00:24:44.849 --> 00:24:47.437
But as the code grows longer,

516
00:24:47.437 --> 00:24:49.688
the difference will become noticeable

517
00:24:54.749 --> 00:24:59.766
Also, I unknowingly wrote like this

518
00:24:59.766 --> 00:25:02.280
This is called a slash

519
00:25:02.280 --> 00:25:05.998
On the keyboard, right next to the right shift key,

520
00:25:05.998 --> 00:25:09.219
under the question mark

521
00:25:09.219 --> 00:25:10.690
That’s the one

522
00:25:10.690 --> 00:25:12.975
If you use it twice like this,

523
00:25:12.975 --> 00:25:15.536
this is called a comment in English

524
00:25:15.536 --> 00:25:16.488
A comment

525
00:25:19.780 --> 00:25:21.514
This is called a comment

526
00:25:21.514 --> 00:25:23.140
There are two types of comments

527
00:25:23.140 --> 00:25:28.078
One way is to comment out a single line

528
00:25:28.078 --> 00:25:31.622
So if you look here, if you do this,

529
00:25:33.849 --> 00:25:35.878
everything from here to the end

530
00:25:35.878 --> 00:25:37.888
becomes a comment, that’s the meaning

531
00:25:41.129 --> 00:25:44.528
And there’s another type of comment

532
00:25:44.528 --> 00:25:46.910
It looks like this

533
00:25:46.910 --> 00:25:49.680
Slash and asterisk

534
00:25:49.680 --> 00:25:51.547
Then an asterisk and a slash

535
00:25:51.547 --> 00:25:53.663
That's the other type

536
00:25:53.663 --> 00:25:55.669
This is a block comment

537
00:25:55.669 --> 00:25:58.556
It creates a specific block

538
00:25:58.556 --> 00:26:00.949
for commenting

539
00:26:00.949 --> 00:26:03.076
Like this

540
00:26:03.076 --> 00:26:04.816
Let's try using this

541
00:26:04.816 --> 00:26:06.904
For example,

542
00:26:06.904 --> 00:26:08.159
we can write it like this

543
00:26:08.159 --> 00:26:11.342
Then from here to here, it will be a comment

544
00:26:12.550 --> 00:26:13.338
It’s a bit different

545
00:26:13.338 --> 00:26:16.053
This one comments out the whole line

546
00:26:16.053 --> 00:26:18.567
While this one allows you to specify the start and end

547
00:26:18.567 --> 00:26:21.037
of a block comment

548
00:26:21.829 --> 00:26:23.076
So, in general,

549
00:26:23.076 --> 00:26:26.910
there are two types of comments

550
00:26:26.910 --> 00:26:28.489
If we talk about C language

551
00:26:28.489 --> 00:26:31.649
or C++,

552
00:26:31.649 --> 00:26:32.979
this is the old method

553
00:26:32.979 --> 00:26:35.471
A commenting method used,

554
00:26:35.471 --> 00:26:37.742
in C language

555
00:26:37.742 --> 00:26:40.606
This is the method used in C++,

556
00:26:40.606 --> 00:26:42.320
I can say that

557
00:26:42.320 --> 00:26:44.535
But since this is C#,

558
00:26:44.535 --> 00:26:45.949
instead of distinguishing like that,

559
00:26:45.949 --> 00:26:47.938
We can understand it

560
00:26:47.938 --> 00:26:50.937
as this one comments by creating a block

561
00:26:50.937 --> 00:26:53.532
And this one comments line by line

562
00:26:53.532 --> 00:26:56.006
That's how it works

563
00:26:59.031 --> 00:27:01.198
Now, let’s go back

564
00:27:01.198 --> 00:27:03.759
If you look here, there’s static

565
00:27:05.125 --> 00:27:07.337
Wait, if we look at the structure here,

566
00:27:07.337 --> 00:27:09.230
there’s also Internal

567
00:27:09.230 --> 00:27:11.314
These all have meanings

568
00:27:12.779 --> 00:27:14.877
I’ll explain these later

569
00:27:14.877 --> 00:27:18.262
when I talk about classes

570
00:27:18.262 --> 00:27:20.540
For now, I’ll talk a bit about this

571
00:27:20.540 --> 00:27:23.859
To explain this briefly,

572
00:27:23.859 --> 00:27:26.815
What we’re seeing here

573
00:27:26.815 --> 00:27:28.989
are what we call variables

574
00:27:28.989 --> 00:27:32.965
In this lecture,

575
00:27:32.965 --> 00:27:35.872
we’ll talk about variables next time

576
00:27:35.872 --> 00:27:38.903
But to put it simply,

577
00:27:38.903 --> 00:27:41.219
a variable is a container

578
00:27:41.219 --> 00:27:42.453
That holds a value

579
00:27:42.453 --> 00:27:44.532
that container is stored somewhere

580
00:27:44.532 --> 00:27:46.274
So this container

581
00:27:46.274 --> 00:27:48.430
is saved somewhere

582
00:27:48.430 --> 00:27:51.093
So, we need to understand

583
00:27:51.093 --> 00:27:53.460
this concept in terms of computer structure

584
00:27:54.847 --> 00:27:58.008
So, we’ll talk more about builds later

585
00:28:00.615 --> 00:28:02.369
Let’s take a look at computer structure

586
00:28:02.369 --> 00:28:04.452
This is how a computer looks

587
00:28:06.076 --> 00:28:08.848
If you open up a computer, you’ll see the motherboard

588
00:28:11.540 --> 00:28:13.304
And somewhere here

589
00:28:13.304 --> 00:28:17.357
is the central processing unit, the CPU

590
00:28:17.357 --> 00:28:19.979
Then memory goes here

591
00:28:19.979 --> 00:28:21.052
This is memory

592
00:28:22.982 --> 00:28:24.773
What we usually call RAM

593
00:28:24.773 --> 00:28:27.179
It’s called Random Access Memory,

594
00:28:27.179 --> 00:28:29.374
like Samsung RAM, Hynix RAM,

595
00:28:29.374 --> 00:28:30.660
and so many more

596
00:28:30.660 --> 00:28:32.261
RAM goes here

597
00:28:32.261 --> 00:28:35.488
And also, SSDs

598
00:28:35.488 --> 00:28:36.619
Things like that go in here

599
00:28:36.619 --> 00:28:40.070
The RAM is long and shaped like this

600
00:28:40.070 --> 00:28:45.203
So these are SSDs

601
00:28:45.203 --> 00:28:47.538
In the past, we used to call them HDD

602
00:28:47.538 --> 00:28:48.829
Hard Disk Drives

603
00:28:48.829 --> 00:28:51.595
That’s what we called them

604
00:28:51.595 --> 00:28:53.356
If you look at it broadly,

605
00:28:53.356 --> 00:28:55.509
this is called the Central Processing Unit

606
00:28:59.920 --> 00:29:02.804
The Central Processing Unit, CPU

607
00:29:02.804 --> 00:29:04.179
Then here’s the memory

608
00:29:04.179 --> 00:29:06.400
This is the main memory

609
00:29:10.819 --> 00:29:13.009
This is called secondary memory

610
00:29:17.437 --> 00:29:19.031
Actually, computers

611
00:29:19.031 --> 00:29:23.221
can be seen as having benchmarked

612
00:29:23.221 --> 00:29:25.380
human brains and concepts

613
00:29:25.380 --> 00:29:27.055
When a person has a brain

614
00:29:27.055 --> 00:29:30.434
The brain is here, right?

615
00:29:30.434 --> 00:29:32.589
What the brain mainly does

616
00:29:32.589 --> 00:29:35.659
is two things

617
00:29:35.659 --> 00:29:37.413
To handle calculations,

618
00:29:37.413 --> 00:29:40.247
and handle memory, right?

619
00:29:40.247 --> 00:29:42.096
So in a computer,

620
00:29:42.096 --> 00:29:45.890
there’s the CPU that handles calculations

621
00:29:45.890 --> 00:29:49.698
and the memory that handles storage

622
00:29:49.698 --> 00:29:51.803
Secondary memory like this

623
00:29:51.803 --> 00:29:54.938
isn’t really like the human body

624
00:29:54.938 --> 00:30:00.297
It’s more like a diary or your phone

625
00:30:00.297 --> 00:30:02.328
where you store things

626
00:30:02.328 --> 00:30:04.547
That way, the memory

627
00:30:04.547 --> 00:30:06.550
can be retrieved again

628
00:30:06.550 --> 00:30:09.239
So you can think of it that way

629
00:30:09.239 --> 00:30:13.569
When we need to handle information,

630
00:30:13.569 --> 00:30:15.626
we need to store it, right?

631
00:30:15.626 --> 00:30:17.088
So here, the parameter

632
00:30:18.909 --> 00:30:21.022
is like a container for storing

633
00:30:21.022 --> 00:30:23.016
Something in memory

634
00:30:23.016 --> 00:30:25.699
This memory is usually thought of

635
00:30:25.699 --> 00:30:27.103
So that container is ultimately

636
00:30:27.103 --> 00:30:29.372
stored in memory

637
00:30:29.372 --> 00:30:31.887
So that memory is usually thought of

638
00:30:31.887 --> 00:30:35.339
as main memory

639
00:30:35.339 --> 00:30:36.548
or secondary memory

640
00:30:36.548 --> 00:30:41.048
To be more precise,

641
00:30:41.048 --> 00:30:43.427
the part of memory

642
00:30:43.427 --> 00:30:45.579
that we use

643
00:30:45.579 --> 00:30:47.528
is the main memory

644
00:30:47.528 --> 00:30:50.121
The secondary memory

645
00:30:50.121 --> 00:30:51.987
is where our files

646
00:30:51.987 --> 00:30:53.400
are actually stored

647
00:30:53.400 --> 00:30:55.646
Of course, strictly speaking,

648
00:30:55.646 --> 00:30:58.504
there’s something called paging techniques

649
00:30:58.504 --> 00:31:01.754
where part of the secondary memory

650
00:31:01.754 --> 00:31:04.979
is used by the main memory

651
00:31:04.979 --> 00:31:07.883
But even without considering that,

652
00:31:07.883 --> 00:31:10.842
You can divide it like this

653
00:31:10.842 --> 00:31:12.966
So that’s the explanation

654
00:31:14.768 --> 00:31:18.085
So that's what it is

655
00:31:18.085 --> 00:31:19.759
This is how it looks like

656
00:31:19.759 --> 00:31:23.871
So, in the end, we’re storing values

657
00:31:23.871 --> 00:31:25.458
in memory

658
00:31:25.458 --> 00:31:28.315
This is what we wrote earlier

659
00:31:28.315 --> 00:31:30.332
when you write it like this,

660
00:31:30.332 --> 00:31:32.094
It gets stored somewhere

661
00:31:32.094 --> 00:31:34.342
and then it comes over here, right?

662
00:31:34.342 --> 00:31:36.707
It’s passed over, and that’s the concept

663
00:31:36.707 --> 00:31:38.339
that we use

664
00:31:38.339 --> 00:31:40.746
So that container is ultimately

665
00:31:42.979 --> 00:31:45.108
stored in memory

666
00:31:45.108 --> 00:31:47.582
Is memory a single space?

667
00:31:47.582 --> 00:31:48.939
No, it’s not

668
00:31:48.939 --> 00:31:51.553
Memory is divided into parts

669
00:31:51.553 --> 00:31:54.155
To put it simply,

670
00:31:54.155 --> 00:31:57.060
it’s divided into four main sections

671
00:31:57.060 --> 00:32:00.663
So it’s split into four areas

672
00:32:00.663 --> 00:32:03.763
There’s the code area

673
00:32:03.763 --> 00:32:06.859
Then the data area

674
00:32:06.859 --> 00:32:10.156
Next is the heap and the stack

675
00:32:10.156 --> 00:32:13.127
These are the areas

676
00:32:13.127 --> 00:32:14.835
But code is usually

677
00:32:14.835 --> 00:32:16.911
what we’ve written in our program

678
00:32:16.911 --> 00:32:20.605
That’s what’s stored as assembly language

679
00:32:20.605 --> 00:32:24.447
The actual code becomes machine language

680
00:32:24.447 --> 00:32:26.992
You can call it machine language

681
00:32:26.992 --> 00:32:28.604
Those machine instructions

682
00:32:28.604 --> 00:32:30.619
are stored in memory

683
00:32:30.619 --> 00:32:33.220
That’s the code area

684
00:32:33.220 --> 00:32:36.070
Then the data area contains static variables

685
00:32:38.900 --> 00:32:41.409
In C#, it’s where static variables

686
00:32:43.699 --> 00:32:45.508
and global variables exist

687
00:32:45.508 --> 00:32:46.764
That's what it is

688
00:32:46.764 --> 00:32:50.459
The heap is the space we create when needed

689
00:32:50.459 --> 00:32:53.279
and remove when it’s no longer necessary

690
00:32:53.279 --> 00:32:55.469
It’s where memory is dynamically allocated

691
00:32:55.469 --> 00:32:59.707
So usually when you create memory

692
00:32:59.707 --> 00:33:02.608
with the New keyword

693
00:33:02.608 --> 00:33:04.108
That memory

694
00:33:04.108 --> 00:33:05.619
is called the heap

695
00:33:05.619 --> 00:33:10.298
The stack is for function parameters

696
00:33:12.900 --> 00:33:15.498
or local variables

697
00:33:17.957 --> 00:33:21.696
Since this is your first time,
it’s fine if you don’t understand everything

698
00:33:21.696 --> 00:33:24.178
But it’s good to have an idea

699
00:33:24.178 --> 00:33:27.140
that memory is divided this way

700
00:33:27.140 --> 00:33:28.550
That's what it is

701
00:33:28.550 --> 00:33:31.349
The key feature of these

702
00:33:31.349 --> 00:33:34.187
is a concept called the Lifecycle

703
00:33:41.048 --> 00:33:42.216
It's called Lifecycle

704
00:33:42.216 --> 00:33:47.009
Simply put, the application app runs,

705
00:33:47.009 --> 00:33:49.481
and then it ends, right?

706
00:33:51.431 --> 00:33:53.981
During this time,

707
00:33:53.981 --> 00:33:56.687
the variables use memory

708
00:33:56.687 --> 00:33:59.476
when they’re created,

709
00:33:59.476 --> 00:34:02.409
and when they disappear

710
00:34:02.409 --> 00:34:03.979
That's the gist of the lifecycle

711
00:34:03.979 --> 00:34:06.002
So, the code will naturally

712
00:34:06.002 --> 00:34:08.382
continue to exist

713
00:34:08.382 --> 00:34:10.393
until the application terminates

714
00:34:10.393 --> 00:34:12.709
The same applies to the data section

715
00:34:12.709 --> 00:34:14.911
Both of these exist while the app is running

716
00:34:16.812 --> 00:34:19.600
and disappear when it terminates

717
00:34:19.600 --> 00:34:23.643
The heap, however, can be created and destroyed by the user

718
00:34:23.643 --> 00:34:26.587
The stack is allocated when a function is called

719
00:34:26.587 --> 00:34:28.408
This process is known as a function call,

720
00:34:28.408 --> 00:34:30.370
when the function call is made, memory is allocated,

721
00:34:30.370 --> 00:34:33.364
and when the function terminates, the memory is freed

722
00:34:33.364 --> 00:34:36.521
For now, you don’t need to fully understand these concepts,

723
00:34:36.521 --> 00:34:39.189
but the key point I want to emphasize here

724
00:34:39.189 --> 00:34:41.673
is the term static,

725
00:34:41.673 --> 00:34:43.288
spelled as static

726
00:34:45.340 --> 00:34:47.788
It is something

727
00:34:47.788 --> 00:34:52.028
that exists from the very beginning

728
00:34:52.028 --> 00:34:54.355
It is created at the start

729
00:34:54.355 --> 00:34:56.047
and remains throughout execution

730
00:34:56.047 --> 00:34:58.159
In other words, static elements always exist

731
00:35:00.260 --> 00:35:02.719
Since they disappear only when the app terminates,

732
00:35:02.719 --> 00:35:04.989
they effectively persist

733
00:35:04.989 --> 00:35:07.100
for the entire runtime of the application

734
00:35:07.100 --> 00:35:09.250
That’s why the static keyword

735
00:35:09.250 --> 00:35:10.349
is used here

736
00:35:10.349 --> 00:35:12.601
So see here

737
00:35:12.601 --> 00:35:15.260
We have static and Main functions

738
00:35:15.260 --> 00:35:17.273
This Main function exists

739
00:35:17.273 --> 00:35:18.752
from the very beginning,

740
00:35:18.752 --> 00:35:20.315
right from the start

741
00:35:21.939 --> 00:35:24.569
That’s why the static keyword is used here

742
00:35:24.569 --> 00:35:26.671
All static elements

743
00:35:26.671 --> 00:35:30.238
are created at the same time,

744
00:35:30.238 --> 00:35:31.298
so they exist together throughout execution

745
00:35:31.298 --> 00:35:32.684
Like this

746
00:35:32.684 --> 00:35:34.539
Now, let’s wrap up

747
00:35:34.539 --> 00:35:37.379
the explanation of Main

748
00:35:37.379 --> 00:35:38.907
The Main function

749
00:35:46.820 --> 00:35:48.693
is referred to as such

750
00:35:50.149 --> 00:35:55.348
It's an C# application

751
00:35:57.580 --> 00:35:59.047
Application,

752
00:36:00.979 --> 00:36:03.332
or app for short

753
00:36:03.332 --> 00:36:06.458
It is the entry point of a C# application

754
00:36:09.540 --> 00:36:11.455
That means it is the very first function

755
00:36:12.643 --> 00:36:15.968
when what starts?

756
00:36:15.968 --> 00:36:18.834
When the app starts

757
00:36:18.834 --> 00:36:21.478
It gets called

758
00:36:23.860 --> 00:36:25.751
when the application starts

759
00:36:25.751 --> 00:36:26.514
That's what it is

760
00:36:26.514 --> 00:36:29.619
This is why Main is known as the entry point

761
00:36:29.619 --> 00:36:31.820
In C#, there is only one entry point,

762
00:36:31.820 --> 00:36:34.610
which means

763
00:36:34.610 --> 00:36:37.409
a program can have

764
00:36:39.659 --> 00:36:40.565
only one Main function

765
00:36:40.565 --> 00:36:42.783
So there's only one Main function

766
00:36:44.694 --> 00:36:45.590
That's what it is

767
00:36:53.780 --> 00:36:55.710
If we visualize this with a diagram,

768
00:36:55.710 --> 00:36:57.124
it would look something like this

769
00:36:58.283 --> 00:37:00.210
There is an operating system,

770
00:37:00.210 --> 00:37:02.712
commonly abbreviated as OS

771
00:37:02.712 --> 00:37:03.914
Operating system

772
00:37:03.914 --> 00:37:05.828
Some examples of OS

773
00:37:09.377 --> 00:37:12.188
include things like

774
00:37:12.188 --> 00:37:12.981
Windows,

775
00:37:16.654 --> 00:37:18.102
which we use a lot,

776
00:37:18.102 --> 00:37:21.286
Mac or Macintosh,

777
00:37:21.286 --> 00:37:23.199
Macintosh

778
00:37:23.199 --> 00:37:27.372
Linux, and Unix

779
00:37:28.461 --> 00:37:30.373
For mobile devices, we have

780
00:37:31.928 --> 00:37:34.899
operating systems like Android

781
00:37:34.899 --> 00:37:37.749
The operating system

782
00:37:37.749 --> 00:37:41.297
runs applications,

783
00:37:41.297 --> 00:37:43.054
which execute within its environment

784
00:37:44.500 --> 00:37:47.134
So, in the OS,

785
00:37:47.134 --> 00:37:50.180
an application runs as a process

786
00:37:50.180 --> 00:37:53.073
When it starts, the very first function that gets called

787
00:37:53.073 --> 00:37:55.045
is the Main function

788
00:37:56.540 --> 00:37:57.603
That's the structure

789
00:37:58.762 --> 00:38:00.953
Applications, in another term,

790
00:38:00.953 --> 00:38:03.528
are also called processes

791
00:38:05.719 --> 00:38:06.917
To explain this further,

792
00:38:06.917 --> 00:38:08.863
it can be a little tricky

793
00:38:08.863 --> 00:38:11.748
If you right-click on your desktop

794
00:38:11.748 --> 00:38:13.750
and open the Task Manager,

795
00:38:13.750 --> 00:38:14.625
here,

796
00:38:15.912 --> 00:38:16.983
you will see a section

797
00:38:16.983 --> 00:38:19.435
labeled Processes

798
00:38:19.435 --> 00:38:22.419
All the running applications are listed here,

799
00:38:22.419 --> 00:38:25.022
including both active applications

800
00:38:25.022 --> 00:38:26.692
and background processes

801
00:38:26.692 --> 00:38:28.235
This means an application

802
00:38:28.235 --> 00:38:30.557
is just one type of process

803
00:38:34.181 --> 00:38:37.979
Hopefully, this gives you a general understanding

804
00:38:37.979 --> 00:38:41.057
This isn’t a difficult concept

805
00:38:41.057 --> 00:38:42.436
Once you grasp the structure,

806
00:38:42.436 --> 00:38:44.304
everything becomes clearer

807
00:38:44.304 --> 00:38:45.699
So that's what it is

808
00:38:45.699 --> 00:38:48.672
Let's summarize this

809
00:38:48.672 --> 00:38:52.149
And there’s one more thing I want to mention

810
00:38:52.149 --> 00:38:56.308
The question here is,

811
00:38:56.308 --> 00:39:00.567
how does C# actually run?

812
00:39:02.300 --> 00:39:05.631
Earlier, I talked

813
00:39:05.631 --> 00:39:07.259
about the build process,

814
00:39:10.139 --> 00:39:15.191
When we talk about builds,

815
00:39:15.191 --> 00:39:17.069
it applies not only to C#

816
00:39:17.069 --> 00:39:20.798
but also to languages like Python,

817
00:39:20.798 --> 00:39:22.966
Java, and more,

818
00:39:22.966 --> 00:39:25.133
like C, and C++

819
00:39:25.133 --> 00:39:27.006
Same thing here

820
00:39:27.006 --> 00:39:28.826
In the build process,

821
00:39:28.826 --> 00:39:32.302
we write code using a structured,

822
00:39:32.302 --> 00:39:36.820
human-readable programming language

823
00:39:36.820 --> 00:39:39.543
For example, in C#, it's a C# code

824
00:39:39.543 --> 00:39:41.256
So this is essentially a file

825
00:39:42.860 --> 00:39:46.665
we write code in .cs files

826
00:39:46.665 --> 00:39:48.818
That's the extension

827
00:39:48.818 --> 00:39:51.692
This code then

828
00:39:51.692 --> 00:39:53.590
needs to be compiled

829
00:39:57.070 --> 00:40:00.192
When we compile it,

830
00:40:00.192 --> 00:40:01.840
it first gets translated

831
00:40:06.506 --> 00:40:08.620
The build process may differ

832
00:40:08.620 --> 00:40:10.342
with different languages

833
00:40:11.936 --> 00:40:13.955
Let me start with this first

834
00:40:13.955 --> 00:40:15.775
For C#,

835
00:40:15.775 --> 00:40:19.309
it gets translated into an intermediate language

836
00:40:19.309 --> 00:40:21.478
this intermediate language is packaged

837
00:40:21.478 --> 00:40:26.117
into either an exe or dll

838
00:40:27.820 --> 00:40:29.881
like .exe

839
00:40:29.881 --> 00:40:31.561
Exe refers

840
00:40:31.561 --> 00:40:33.031
to executable file

841
00:40:33.031 --> 00:40:34.750
Dll means

842
00:40:34.750 --> 00:40:37.120
dynamic link library

843
00:40:37.120 --> 00:40:39.404
So it's a dynamic link library

844
00:40:40.760 --> 00:40:42.768
That's the file extension we get

845
00:40:42.768 --> 00:40:44.587
Metadata is also generated alongside these files,

846
00:40:48.013 --> 00:40:50.641
so we have these here

847
00:40:50.641 --> 00:40:52.445
So we have these files

848
00:40:52.445 --> 00:40:56.547
Now, to actually execute these files,

849
00:40:56.547 --> 00:40:59.357
the operating system needs to interpret and run them

850
00:41:00.634 --> 00:41:03.369
Now, when the necessary information

851
00:41:03.369 --> 00:41:06.081
moves through this process,

852
00:41:06.081 --> 00:41:07.387
something happens here

853
00:41:09.815 --> 00:41:12.229
There’s something called the Common Language Runtime

854
00:41:12.229 --> 00:41:14.127
or CLR

855
00:41:14.127 --> 00:41:17.688
It's called Common Language Runtime

856
00:41:17.688 --> 00:41:19.783
During compilation, the intermediate language

857
00:41:19.783 --> 00:41:23.075
is usually called CIL,

858
00:41:23.075 --> 00:41:28.354
or Common Intermediate Language

859
00:41:28.354 --> 00:41:30.704
That's CIL

860
00:41:30.704 --> 00:41:34.330
So, CIL is generated as an intermediate language

861
00:41:34.330 --> 00:41:37.199
In Java, this would be referred to as bytecode

862
00:41:37.199 --> 00:41:40.781
It's called a bytecode

863
00:41:42.969 --> 00:41:45.565
But calling it an intermediate language

864
00:41:45.565 --> 00:41:47.822
is more accurate in this case

865
00:41:47.822 --> 00:41:49.499
Anyway, this intermediate language

866
00:41:49.499 --> 00:41:51.500
is created like so,

867
00:41:51.500 --> 00:41:54.443
and then something called CLR processes it

868
00:41:54.443 --> 00:41:58.088
CLR converts it into native code

869
00:42:02.899 --> 00:42:04.709
That’s what happens

870
00:42:04.709 --> 00:42:06.838
In Java, this process is handled

871
00:42:06.838 --> 00:42:08.658
by something called VM or Virtual Machine

872
00:42:08.658 --> 00:42:11.561
C# has a very similar structure to Java

873
00:42:11.561 --> 00:42:14.538
This is why we call it the .NET environment

874
00:42:16.927 --> 00:42:18.560
It’s commonly known as the .NET Framework

875
00:42:18.560 --> 00:42:21.540
A .Net environment

876
00:42:21.540 --> 00:42:23.812
When we build C# code,

877
00:42:23.812 --> 00:42:26.840
it produces an intermediate language file

878
00:42:26.840 --> 00:42:28.106
This file is then

879
00:42:28.106 --> 00:42:31.158
processed inside the operating system

880
00:42:31.158 --> 00:42:34.758
by a virtual machine, or the CLR,

881
00:42:34.758 --> 00:42:36.852
which converts it into native code

882
00:42:36.852 --> 00:42:39.186
That native code is what the operating system

883
00:42:39.186 --> 00:42:40.266
actually executes

884
00:42:41.820 --> 00:42:44.871
That’s the structure of the process

885
00:42:44.871 --> 00:42:46.650
So, all we need to do is write the code

886
00:42:46.650 --> 00:42:48.024
Then, with this,

887
00:42:48.024 --> 00:42:49.926
when we compile it,

888
00:42:49.926 --> 00:42:52.189
an intermediate language file like .exe or .dll is created

889
00:42:52.189 --> 00:42:55.765
With that file, the program can be run

890
00:42:55.765 --> 00:42:57.848
on various operating systems

891
00:42:57.848 --> 00:42:59.633
So that's the Virtual Machine

892
00:42:59.633 --> 00:43:01.162
That’s why it’s all

893
00:43:01.162 --> 00:43:02.965
called a virtual machine

894
00:43:05.500 --> 00:43:07.522
Through this virtual machine,

895
00:43:07.522 --> 00:43:10.287
different operating systems

896
00:43:10.287 --> 00:43:12.266
are able to run the program

897
00:43:12.266 --> 00:43:14.373
The system is pre-configured

898
00:43:14.373 --> 00:43:15.989
so that it can execute properly regardless of the OS

899
00:43:15.989 --> 00:43:19.081
That’s how execution works

900
00:43:19.081 --> 00:43:22.699
This is the build process of C#

901
00:43:22.699 --> 00:43:25.846
From building to execution,

902
00:43:25.846 --> 00:43:27.710
this is the full process

903
00:43:27.710 --> 00:43:30.103
In C, the process is different

904
00:43:30.103 --> 00:43:31.280
It's not like this

905
00:43:31.280 --> 00:43:34.769
C first goes through preprocessing,

906
00:43:34.769 --> 00:43:38.416
then compilation

907
00:43:40.129 --> 00:43:42.233
After that, it generates object files

908
00:43:42.233 --> 00:43:45.624
Then, the linker takes these object files and links them together,

909
00:43:45.624 --> 00:43:49.139
combining them into a final .exe file

910
00:43:49.139 --> 00:43:50.180
That's how it works

911
00:43:50.180 --> 00:43:55.176
For this, the compiled and linked executable is different

912
00:43:55.176 --> 00:43:59.379
Each OS generates a different type of executable

913
00:43:59.379 --> 00:44:02.862
so C programs aren’t inherently cross-compatible

914
00:44:02.862 --> 00:44:05.208
C# was designed to be more universal,

915
00:44:05.208 --> 00:44:06.849
unlike other languages

916
00:44:06.849 --> 00:44:10.428
So it first compiles into an intermediate language

917
00:44:10.428 --> 00:44:14.711
Then, this intermediate code is processed

918
00:44:14.711 --> 00:44:17.699
by a Common Language Runtime or CLR,

919
00:44:17.699 --> 00:44:20.476
which acts as a virtual machine to convert it

920
00:44:20.476 --> 00:44:22.784
into native code for the specific OS

921
00:44:22.784 --> 00:44:24.699
That's how it works

922
00:44:24.699 --> 00:44:28.134
Let's summarize what we've learned today

923
00:44:28.595 --> 00:44:30.322
Summary
Installing Visual Studio & Running Hello World
Install Visual Studio through Visual Studio Installer

924
00:44:30.322 --> 00:44:32.042
The installer expands Visual Studio’s functionality
Create a new project → Select C# under All Languages (L)
Select Console under All Project T

925
00:44:32.042 --> 00:44:33.813
Enter Project Name and Solution Name, then click Create
WriteLine Hello World

926
00:44:33.813 --> 00:44:35.506
Debug: Creates an executable for debugging
Release: Creates an executable for distribution

927
00:44:35.506 --> 00:44:37.926
Programming Basics and C# Compiler Execution Process
Build: The process where C# code becomes an executable
Main Function: The first function call

928
00:44:37.926 --> 00:44:40.221
Compilation: The step before code turns into an executable
Variables: Store values in memory
Memory Sections
Code: Machine code stored in memory

929
00:44:40.221 --> 00:44:42.525
Data: Stores static variables
Heap: Allocates and deallocates memory as needed
Stack: Stores function parameters and local variables

930
00:44:42.535 --> 00:44:45.485
C# Compiler Execution Process
Write C# Code
Compile C# files, generating .exe or .dll intermediate language

931
00:44:45.485 --> 00:44:48.446
CLR (Common Language Runtime) in .NET
converts this into native code
Native code runs on the OS