Learn C#

Visual Studio Code (VS Code) is a free, lightweight, and powerful code editor from Microsoft. It's the most popular editor for C# development outside of full Visual Studio and works on Windows, macOS, and Linux. Steps: 1. Download VS Code from https://code.visualstudio.com and run the installer. 2. Open VS Code and confirm it launches successfully. Recommended settings to configure after installation (File → Preferences → Settings): - Enable 'Format On Save' (editor.formatOnSave: true) to auto-format code every time you save. - Turn on 'Bracket Pair Colorisation' for easier brace matching. Next you will install the C# Dev Kit extension — see S-2 for that step.

// This file verifies that VS Code + C# Dev Kit are working correctly.
// Press F5 (or Run > Start Debugging) to execute.
// You should see a message printed in the integrated terminal.

using System;

class VsCodeSetupCheck
{
    static void Main()
    {
        Console.WriteLine("✓ VS Code is configured correctly!");
        Console.WriteLine("  Editor:    Visual Studio Code");
        Console.WriteLine("  Extension: C# Dev Kit");
        Console.WriteLine("  Runtime:   " +
            System.Runtime.InteropServices.RuntimeInformation.FrameworkDescription);
        Console.WriteLine();
        Console.WriteLine("You're ready to start coding in C#.");
    }
}

The C# Dev Kit is a free, Microsoft-built extension for VS Code that adds everything you need to write, debug, and manage C# projects — including IntelliSense, a Solution Explorer, debugging support, and project templates. Steps: 1. Open VS Code and click the Extensions icon in the Activity Bar (or press Ctrl+Shift+X / Cmd+Shift+X). 2. In the search box type: C# Dev Kit 3. Select the extension published by Microsoft (identifier: ms-dotnettools.csdevkit). 4. Click Install. VS Code will also automatically install the base C# extension as a dependency. 5. Optionally, also install the .NET Install Tool extension (ms-dotnettools.vscode-dotnet-runtime) — it can install the .NET SDK for you if it is not already present on your machine. You can also install it directly from the VS Code Marketplace: https://marketplace.visualstudio.com/items?itemName=ms-dotnettools.csdevkit Once installed, reload VS Code when prompted. You should see a new Solution Explorer panel appear in the Activity Bar, confirming the extension is active.

// After installing C# Dev Kit, open the Command Palette
// (Ctrl+Shift+P / Cmd+Shift+P) and run:
//   .NET: New Project
// Choose "Console App", give it a name, and VS Code will
// scaffold the project and open Program.cs for you.

// You can also verify the extension is active by checking that
// IntelliSense suggestions appear as you type below:

using System;

class ExtensionCheck
{
    static void Main()
    {
        // Try typing 'Console.' — IntelliSense should list methods.
        Console.WriteLine("C# Dev Kit is installed and working!");
        Console.WriteLine("IntelliSense, debugging, and Solution Explorer are ready.");
    }
}

The .NET SDK is the foundation for every course on this page. It includes the C# compiler, runtime, and command-line tools. It's free, open-source, and works on Windows, macOS, and Linux. Steps: 1. Visit https://dotnet.microsoft.com/download and download the latest .NET SDK (choose the LTS version for stability). 2. Run the installer and follow the on-screen prompts. 3. Open a terminal (Command Prompt, PowerShell, or Terminal) and run: dotnet --version 4. If you see a version number (e.g. 8.0.x) your installation is successful. Once installed, paste the code below into any IDE and run it to confirm everything works.

// Paste this into your IDE and run it to verify your .NET setup.
// You should see version info and a success message printed to the console.

using System;

class VerifySetup
{
    static void Main()
    {
        Console.WriteLine("=== .NET Setup Verification ===");
        Console.WriteLine("Runtime: " + System.Runtime.InteropServices.RuntimeInformation.FrameworkDescription);
        Console.WriteLine("OS:      " + System.Runtime.InteropServices.RuntimeInformation.OSDescription);
        Console.WriteLine();
        Console.WriteLine("✓ Your .NET environment is ready!");
        Console.WriteLine("You can now work through any course on this page.");
    }
}

Once VS Code and the .NET SDK are installed, there are two ways to build and run a C# program: using the integrated terminal or using VS Code's built-in Run & Debug panel. Method 1 — Terminal (recommended for beginners): 1. Open VS Code and create a new folder for your project. 2. Open the integrated terminal (Ctrl+` / Cmd+`). 3. Run: dotnet new console -n MyFirstApp This creates a new console project in a subfolder called MyFirstApp. 4. Navigate into it: cd MyFirstApp 5. Open the generated Program.cs file and replace its contents with your code. 6. Run: dotnet run Your program compiles and executes immediately. Output appears in the terminal. Method 2 — Run & Debug panel: 1. Open the project folder in VS Code (File → Open Folder). 2. Open Program.cs and press F5 (or go to Run → Start Debugging). 3. If prompted to select a debugger, choose C#. 4. VS Code will build the project and launch it in the integrated terminal. Tip: dotnet run builds and runs in one step. For a build-only check without running, use dotnet build. To run without rebuilding, use dotnet run --no-build.

// This is the entry point of a standard .NET console application.
// Run it with: dotnet run  (from the terminal inside your project folder)
// Or press F5 inside VS Code with the C# Dev Kit extension installed.

using System;

class BuildAndRun
{
    static void Main()
    {
        Console.WriteLine("Build successful!");
        Console.WriteLine("Your C# program is running from VS Code.");
        Console.WriteLine();

        // dotnet --version prints the SDK version to confirm your toolchain
        Console.WriteLine("Useful terminal commands:");
        Console.WriteLine("  dotnet new console -n MyApp  → create a new project");
        Console.WriteLine("  dotnet build                 → compile without running");
        Console.WriteLine("  dotnet run                   → build and run");
        Console.WriteLine("  dotnet run --no-build        → run without rebuilding");
    }
}