Compiling/Executing a C# Source File in Command Prompt

Question

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

Coronado

For those who are interested: I have written a batch file CompileCS.cmd which allows you to compile (and optionally run) a C# file. It uses csc.exe internally and invokes the most recent version found on the local PC. You can find the the batch program 'CompileCS' here at StackOverflow, where I answered how to obtain the most recent csc.exe installed. – Lao

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

Cupbearer

if I remember correctly, you can only compile to and exe if you have a static class with a Main method. – Noh

The compiler warns you these days if you haven't, but good point I'll add that to the answer, thanks. – Cupbearer

This is awesome. Needed to compile a tiny C# app and have no interest in touching Visual Studio. Thanks! – Hannover

In Win10, I found mine there: C:\Program Files (x86)\MSBuild\14.0\Bin\csc.exe – Armoured

What about .Net 8 ? I have these folders: v1.0.3705,v1.1.4322,v2.0.50727,v4.0.30319? – Mordant

In 2024 the steps are - download .NET 4.8.1 and install it - at the command line use C:\Windows\Microsoft.NET\Framework64\v4.0.30319\csc.exe /t:exe /out:cs_HelloWorld.exe cs_HelloWorld.cs perfect. – Serge

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.

Mudslinger

Answer 3

You can compile a C# program :

c: > csc Hello.cs

You can run the program

c: > Hello

Archaean

What if I use additional libraries? I'm getting errors that assemblies are not found... How to fix this? – Ladybird

You'd have to make sure first that the path to the compiler is in the environment variables. – Kyphosis

@NikasŽalias. E.g. csc Hello.cs -langversion:latest -reference:System.Net.Http.dll – Algology

Answer 4

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!

Ternary

Answer 5

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.

Hui

I do use the IDE. But I needed to know. It just doesn't feel right not knowing! Thanks a lot for your response. – Coronado

+1 for NAnt! LINQPad is very good for experimenting with code fragments: linqpad.net – Bales

Answer 6

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.

Inspiratory

Answer 7

PowerShell can execute C# code out of the box.

One liner to compile & execute a file:

(Add-Type -Path "Program.cs" -PassThru)::Main() #'Main' is the entry point

Supposed you have a .cs file like this:

using System;
public class Program
{
    public static void Main()
    {
        Console.WriteLine("Hello from C#");
    }
}

Again

How would you do this with the newer no-Program-class style CS file? Like it literally contains System.Console.WriteLine("Hello"); – Stater

Answer 8

I found a simple way to do this if you have the correct system and environmental variables set up and your path is properly configured.

you just need to run in the directory of the project

dotnet new console --> this will generate the required files such as the .csproj. it will also generate a Program.cs file which it automatically uses as the entry point, if you have other files with your static Main method you can remove this file and it should find the Main entry point automatically.

then all you need to do to run is dotnet run and it should compile and run automatically

this was how i managed to get my projects working in vs code using gitbash as my terminal. Also I have VS 2019 installed, i used the .net 5.0 framework from this as my system variables. This was the simplest solution i found for basic console programs. It also allows you to add custom imports in your .csproj file

Stumper

This is the answer that I was looking for. I had to find it somewhere else and come back to this question to make sure someone had mentioned it. Also, dotnet build will make a .exe file. – Rubric

Answer 9

Add to path

C:\Windows\Microsoft.NET\Framework\v3.5

To Compile:

csc file.cs

To Execute:

file

Unionize

Answer 10

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.

Strathspey

Answer 11

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

Thoma

Answer 12

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!

Suzette

Answer 13

If you have installed Visual Studio then you have Developer Command Prompt for VS. You can easily build your program using csc command and run your application with the name of the application inside the developer command prompt.

You can open Developer command prompt as given below.

Start => Developer Command Prompt for VS

Hope this helps!

Disturbance

can you explain how this actually answers the question? how will this help with using the command line? – Stumper

@Stumper You can easily build your program using csc command and run your application with the name of the application inside the developer command prompt. Did you at least read the answer before commenting and downvoting?? I wonder how two people found this helpful. – Disturbance

of course i read it. i just didnt find it helpful or clear – Stumper

@Stumper OK. Thank you for you for your feedback :) – Disturbance

Answer 14

# File    : csharp.ps1
# Purpose : Powershell Script to compile a csharp console application from powershell prompt

try {
    # CSharp Compiler
    #$csc = "C:\Windows\Microsoft.NET\Framework\v3.5\bin\csc.exe"
    $csc = "C:\Windows\Microsoft.NET\Framework\v4.0.30319\csc.exe"
    # NOTE: if this path doesn't work search Framework folder for csc.exe

    $ErrorActionPreference = 'Stop'

    if ($args.Count -eq 0) {
        write-host "`nUSAGE: csharp.ps1 (console_application.cs)"
        exit 1
    }

    $file = $args[0];
    if (-not(test-path $file)) {
        throw "file doesn't exist: $file"   
    }
    
    $cmd = "$csc /nologo  /t:exe  /out:${file}.exe $file"

    write-host  -ForegroundColor Green "`nx: $cmd"
    invoke-expression $cmd  
}   
catch { 
    write-host -ForegroundColor Red "`nEXCEPTION: $_"
}
finally {
    write-host ""
}

// File: helloworld.cs
using System;

namespace MyProgram
{
    class Program
    {
        public static void Main(string[] args)
        {
            Console.Write("Hello World...");
            Console.ReadKey(true);
        }
    }
}

PS> .\csharp.ps1 helloworld.cs

Inflammable

This is worth a vote for the all important Console.ReadKey(true); – Serge

Answer 15

C:\Program Files (x86)\Microsoft Visual Studio\2017\Professional\MSBuild\15.0\Bin\Roslyn

this is where you can find the c# compiler that supports c#7 otherwise it will use the .net 4 compilers which supports only c# 5

Restaurateur

Answer 16

• Search "Path" in windows
• Select "Edit the system environment.."
• Click on "Environment Variable" right bottom
• Double Click on Path in Variable Section
• Click on New and add the path (you Want to add)
• Click Okay Okay Okay

for me to run csc from command Prompt

Added this "C:\Windows\Microsoft.NET\Framework\v4.0.30319" to path

then open command prompt where my file is located, and ran this

PS C:\Users\UserName\Downloads\Mouse> csc.exe Mouse.cs

Schlosser

Answer 17

dotnet

This is oooold. But since this is where you end up as a beginner when you ask questions to understand how to use C# like C or C++ in a console using compilers without Visual Studio CE (highly recommended for C# btw if you aren't already using it) you end up getting more confused within the lingo of .NET framework and libraries and SDKs. If someone like you stumbles upon my answer as a complete beginner:

1. Understand the difference between Framework and SDK.

2. Understand what C# is and what .NET is.

3. THIS: https://dotnet.microsoft.com/learn/dotnet/hello-world-tutorial/intro

You'll pick up the rest along the way. But instead of using framework I suggest using the SDK and mostly sticking to VS. As for me, I learned C# for unity and mostly game dev.

Also Google is your friend. Ask Questions, stay curious.

Laresa