C# (Csharp) - csc.exe, the C# compiler

Hello koalas,

Here is my demo how to create a wonderful application to demonstrate how the C# compiler (csc.exe) works.

Create folder and files

Firtly, create a folder called "MyApp".

Then create 2 files: Program.cs and MyLibrary.cs

Add this code to each file:

Program.cs:

using System;
using MyLibrary;

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

            // Use of my library "Library.cs"
            Car car = new();
            Console.WriteLine(car.Start());
            Console.WriteLine(car.Stop());

            Console.ReadLine();
        }
    }
}

MyLibrary.cs:

namespace MyLibrary
{
    public class Car
    {
        public string Start()
        {
            return "My car starts.";
        }

        public string Stop()
        {
            return "My car stops.";
        }
    }
}

Check access to csc.exe

Then open a shell (cmd, PowerShell, or other) and verify that you have access to the C# compiler by typing: csc.exe -version

An example of what you should have before to start compiling your application:

If you have no access to csc.exe command you have to add it to your system variable.

Firstly, you have to find out where your csc.exe compiler is.

It has 2 places to find it out but be careful because it's not the same one!

The C# compiler include with your Windows is at:

"C:\windows\Microsoft.NET\Framework64\[Version]\csc.exe"

Per example:
Version: v4.0.30319

Information: "csc.exe -version" command returns version 4.8.xyz. This version is include in .NET Framework 4.8 that is a part of Windows by default.

The C# compiler include with Visual Studio is at:

"C:\Program Files\Microsoft Visual Studio\[Edition]\[Your Version]\MSBuild\Current\Bin\Roslyn\csc.exe"

Per example:
Edition = 2017, 2019, or 2022
Your version = Preview, Community, Professional, or Enterprise

Information: "csc.exe -version" command returns version 4.0.xyz. This version is include in Visual Studio 2022 and is NOT a part of Windows by default.

Now, add the path of your compiler (csc.exe) to your "Environment variables":

Check everything

Now, you have:

• Your application "entry point" (Program.cs)
• Your library, full of methods 😀 (MyLibrary.cs)
• Access to the C# compiler (csc.exe)

You are ready to start compiling your application (MyApp.exe).

Compiling your application

You have to type 2 commands to compile your application:

1. A command to compile your library first
2. A command to compile your application and link the library to it

Here are the commands separated by a semi-colon(;):

csc.exe .\MyLibrary.cs /target:library /out:MyLibrary.dll;csc.exe .\Program.cs /target:exe /out:MyApp.exe /r:MyLibrary.dll

Result

If you run your application (MyApp.exe), you should get this:

I hope you enjoyed this article.

Didier

Sources used