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 it, 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, just type MyApplication followed by <ENTER> at 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

Answer 2

Another way to compile C# programs (without using Visual Studio or without having it installed) is to create a user variable in environment variables, namely "PATH".

Copy the following path in this variable:

"C:\Windows\Microsoft.NET\Framework\v4.0.30319"

or depending upon which .NET your PC have.

So you don't have to mention the whole path every time you compile a code. Simply use

"C:\Users\UserName\Desktop>csc [options] filename.cs"

or wherever the path of your code is.

Now you are good to go.

Answer 3

You can compile a C# program :

c: > csc Hello.cs

You can run the program

c: > Hello

Answer 4

While it is definitely a good thing knowing how to build at the command line, for most work it might be easier to use an IDE. The C# express edition is free and very good for the money ;-p

Alternatively, things like snippy can be used to run fragments of C# code.

Finally - note that the command line is implementation specific; for MS, it is csc; for mono, it is gmcs and friends.... Likewise, to execute: it is just "exename" for the MS version, but typically "mono exename" for mono.

Finally, many projects are build with build script tools; MSBuild, NAnt, etc.

Answer 5

Here is how to install MSBuild with standalone C# 7.0 compiler which is no longer bundled in the latest .Net Framework 4.7:

Is it possible to install a C# compiler without Visual Studio?

Then just run

"C:\Program Files (x86)\Microsoft Visual Studio\2017\BuildTools\MSBuild\15.0\Bin\Roslyn\csc.exe" MyApplication.cs

to compile single source file to executable.

Also note that .Net Core doesn't support compiling single source file without preconfigured project.

Answer 6

For the latest version, first open a Powershell window, go to any folder (e.g. c:\projects\) and run the following

# Get nuget.exe command line
wget https://dist.nuget.org/win-x86-commandline/latest/nuget.exe -OutFile nuget.exe

# Download the C# Roslyn compiler (just a few megs, no need to 'install')
.\nuget.exe install Microsoft.Net.Compilers

# Compiler, meet code
.\Microsoft.Net.Compilers.1.3.2\tools\csc.exe .\HelloWorld.cs

# Run it
.\HelloWorld.exe    

An example HelloWorld.cs

using System;

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

You can also try the new C# interpreter ;)

.\Microsoft.Net.Compilers.1.3.2\tools\csi.exe
> Console.WriteLine("Hello world!");
Hello world!

Answer 7

You can build your class files within the VS Command prompt (so that all required environment variables are loaded), not the default Windows command window.

To know more about command line building with csc.exe (the compiler), see this article.

Answer 8

LinqPad is a quick way to test out some C# code, and its free.

Answer 9

Once you write the c# code and save it. You can use the command prompt to execute it just like the other code.

In command prompt you enter the directory your file is in and type

To Compile:

mcs yourfilename.cs

To Execute:

mono yourfilename.exe 

if you want your .exe file to be different with a different name, type

To Compile:

mcs yourfilename.cs -out:anyname.exe 

To Execute:

mono anyname.exe 

This should help!

Answer 10

In Windows systems, use the command csc <filname>.cs in the command prompt while the current directory is in Microsoft Visual Studio\<Year>\<Version>

There are two ways:

Using the command prompt:

1. Start --> Command Prompt
2. Change the directory to Visual Studio folder, using the command: cd C:\Program Files (x86)\Microsoft Visual Studio\2017\ <Version>
3. Use the command: csc /.cs

Using Developer Command Prompt :

1. Start --> Developer Command Prompt for VS 2017 (Here the directory is already set to Visual Studio folder)

2. Use the command: csc /.cs

Hope it helps!