.CS

Introduction

A .cs file holds source code in C#, Microsoft’s language for the .NET platform. The C# compiler turns the files of a project into a .NET assembly: a PE .exe or .dll that holds bytecode for the .NET runtime. The files that belong to a project, and the libraries it uses, are listed in a .csproj project file.

C# is also the scripting language of the Unity game engine and of the Godot engine’s .NET edition.

Structure

A C# source file is plain text, usually UTF-8. It starts with using directives, then a namespace and the types in it: classes, structs, interfaces, enums and records. Unlike Java, a file may hold any number of public types with any names, and a partial class can be split across several files. Since C# 9, one file in a program may hold top-level statements instead of a Main method.

using System;

namespace Example;

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

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