Compiling/Executing a C# Source File in Command Prompt

Question

How do you compile and execute a .cs file from a command-prompt window?

Answer 1

CSC.exe is the CSharp compiler included in the .NET Framework and can be used to compile from the command prompt. The output can be an executable ".exe", if you use "/target:exe", or a DLL; If you use /target:library, CSC.exe is found in the .NET Framework directory,

e.g. for .NET 3.5, c:\windows\Microsoft.NET\Framework\v3.5\.

To run, first, open a command prompt, click "Start", then type cmd.exe.
You may then have to cd into the directory that holds your source files.

Run the C# compiler like this:

  c:\windows\Microsoft.NET\Framework\v3.5\bin\csc.exe 
            /t:exe /out:MyApplication.exe MyApplication.cs  ...

(all on one line)

If you have more than one source module to be compiled, you can put it on that same command line. If you have other assemblies to reference, use /r:AssemblyName.dll .

Ensure you have a static Main() method defined in one of your classes, to act as the "entry point".

To run the resulting EXE, type MyApplication, followed by <ENTER> using the command prompt.

This article on MSDN goes into more detail on the options for the command-line compiler. You can embed resources, set icons, sign assemblies - everything you could do within Visual Studio.

If you have Visual Studio installed, in the "Start menu"; under Visual Studio Tools, you can open a "Visual Studio command prompt", that will set up all required environment and path variables for command line compilation.

While it's very handy to know of this, you should combine it with knowledge of some sort of build tool such as NAnt, MSBuild, FinalBuilder etc. These tools provide a complete build environment, not just the basic compiler.

On a Mac

On a Mac, syntax is similar, only C sharp Compiler is just named csc:

$ csc /target:exe /out:MyApplication.exe MyApplication.cs ...

Then to run it :

$ mono MyApplication.exe