Introduction

C# is an object-oriented programming language developed by Microsoft for Web application development to compete against Java and runs on ASP.NET. However, it can be used to develop desktop applications as well. The following Hello World sample program in C# should give you a sense of how C# program looks.

using System;

namespace HelloWorld
{
  class Program
  {
    static void Main(string[] args)
    {
      Console.WriteLine("Hello World!");    
    }
  }
}

                

C# was made for developing web applications, and it was, and still is not meant to be general purpose programming language like C, C++, Java or Python. However, it still can be used to develop console and windows applications. In this unit, we cover the fundamentals of programming in C# for general purposes.

Setup VS Code for C# programming

To be able to program in C#, you will need to set up a code editor, ideally an IDE such as VS Code. This can be done in the following steps:

1. If you haven’t, install the latest Visual Studio Code from https://code.visualstudio.com/download which is free and yet very powerful.
2. Install C# extension for Visual Studio Code (latest version) this can be installed from within VS Code, by clicking the extension button on the left-side bar, and then search for C#, and then click install, as shown below.
   
   
3. Install the latest .NET SDK from https://dotnet.microsoft.com/download/dotnet/. It is .NET 7.0 SDK at the time of writing. It can be installed from https://dotnet.microsoft.com/en-us/download/dotnet/7.0 , choose the SDK for your platform, as shown below:
   
   
   
   

Please note that for learning purposes, you’d better download and use the latest release so that you will not miss out any new features. For developers, you may choose the latest release that has long term support from Microsoft.

The Visual Studio Code instructions use the .NET CLI for ASP.NET Core development functions such as project creation. You can follow these instructions on macOS, Linux, or Windows and with any code editor. Minor changes may be required if you use something other than Visual Studio Code.

With VS Code set up for C# programing, you can now create a .NET project for a console application using command dotnet new console, which will create the following subfolder and files:



Among the two files and two directories, bin subdirecotry will hold the executables and libraries, obj will hold intermediate object files, csharp.csproj is the project file containing configrations of the project, and the Program.cs is a simple C# source file containing only one line of comment and one line of code, as shown below:

    // See https://aka.ms/new-console-template for more information
    Console.WriteLine("Hello, World!");                          
                

Now in the terminal window of VS Code (open one if there is no terminal), and run command dotnet run , you will see the Hello World has been printed out in the terminal, as shown below:

Behind the scene, dotnet run comamnd generated several files under the bin and obj subdirectory, as shown below:

Congratulations! Now you know how to setup VS Code as your IDE and write simple C# programs within VS Code.