Lab: Editing, Compiling, and Running with Visual Studio Code#

This lab shows how to create, edit, compile, and run a small C# console program using Visual Studio Code and the .NET command-line tools. This is the recommended graphical editor workflow for current versions of this course.

Prerequisites#

Install these tools before starting:

The .NET SDK, which provides the dotnet command.
Visual Studio Code.
The Microsoft C# Dev Kit extension for Visual Studio Code.

Microsoft’s current setup guides are:

Check that the .NET SDK is available by opening a terminal and entering:

dotnet --version

You should see a version number. If you get a “command not found” message, install the .NET SDK or fix your terminal path before continuing.

Create a Project#

Choose a folder where you want to keep your course work. In a terminal, move to that folder and create a new console project:

mkdir hello-code
cd hello-code
dotnet new console --use-program-main

The --use-program-main option keeps the generated program close to the style used in this book: an explicit class with a Main method. Without that option, current .NET templates use a shorter style called top-level statements, which is useful later but less helpful while learning the basic structure of C# programs.

Open the Project in Visual Studio Code#

From the same terminal, open the project folder:

code .

If the code command is not available, open Visual Studio Code manually and use File -> Open Folder… to open the hello-code folder.

In Visual Studio Code, open Program.cs. Replace its contents with:

using System;

class Hello
{
   static void Main()
   {
      Console.WriteLine("Hello, world!");
   }
}

Save the file. A quick way to save is Command-S on macOS or Ctrl-S on Windows and Linux.

Build the Program#

Open the integrated terminal in Visual Studio Code with Terminal -> New Terminal. Make sure the terminal is still in the project folder, where the .csproj file is located.

Build the project:

dotnet build

If the build succeeds, you should see a message ending with something like:

Build succeeded.

If the build fails, read the first compiler error carefully. Check for common typing mistakes: missing semicolons, mismatched braces, misspelled names, or quotes that do not match.

Run the Program#

Run the project:

dotnet run

You should see:

Hello, world!

Try changing the string inside Console.WriteLine. Save, then run again:

dotnet run

For small programs, dotnet run is the command you will use most often. It builds the project if necessary and then runs it.

What Files Were Created?#

The project folder contains files and folders created by the .NET tools:

Program.cs contains your C# source code.
The .csproj file describes the project to the .NET build tools.
bin and obj contain generated build output.

You normally edit Program.cs and other .cs files. You normally do not edit files in bin or obj.

Exercise#

Modify the program so that it prints two separate lines. Build and run it. Then intentionally remove one semicolon, build again, and read the compiler error. Put the semicolon back and verify that the program runs.

Lab: Editing, Compiling, and Running with Visual Studio Code

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