FAQ: Compiling and Running C# Programs

[LaRoza]

Working on the rest, post suggestions as well. I am not skilled or experienced in C#

So you're willing to write your own C# programs, or simply compile someone else's code? This guide will get you started...

This FAQ assumes you're trying to compile error-free code. To actually learn the C# languages, see the How to start programming thread.

Also remember that although C# is now an ECMA standard, and mono and gmcs follow it (at this point, up to 2.0 fully), many popular libraries used by C# in Windows are not part of the standard.

0.a. Make sure the third party repositories are enabled

The easiest way to do this is open Applications->Add/Remove and select "All Available Applications".

0.b. Make sure the mono-gmcs package is installed

This package installs the essential tools needed to write and run C# programs.

sudo aptitude install mono-gmcs

1. Compiling your first C# program

Copy & paste this code into a new file. Save the file as Main.cs

//First C# Program
using System;

namespace Main
{
   class Welcome
   {
      public static void Main( string[] args )
      {
          Console.Write("Hello world\n");
      }
   }
}//Matching brace. Some people can't be pleased... 

Open a terminal, go to the directory where you saved Main.cs, and type:

gmcs Main.cs

If all went fine, nothing is printed and you get back to the shell. Now, run it:

mono Main.exe

"Hello World!" gets printed in the terminal.

Explanations:

• gmcs is the C# compiler
• obviously, Main means that the compiler must compile this file.
• mono Main.exe runs the newly compiled executable.

2. Paranoid programming is good for your health!

Many beginners want to avoid compiler errors and warnings at any cost, which often leads them to ignore the "cryptic" messages the compiler outputs and to tinker anxiously with the relevant line until the error goes away.
Don't fall in that trap! The compiler is your friend, the messages it outputs are kind advices rather than punishments. You should really take the time to try and understand those messages, this is a very good way to improve your code's quality.

As a matter of fact, most seasoned programmers set the compiler's warning level as high as possible, so that it catches the little errors they make when they aren't paying much attention.

**Help needed** Post in thread to recommend content or deletion of this section.


3. Useful tips

**Help needed** Post in thread to recommend content or deletion of this section.

4. Read the manual!

Plain old manpage:

man gmcs
man mono

Naturally, the Documentation and Tutorial on the Mono project site http://www.mono-project.com/ are good to visit.

You can use any editor, but MonoDevelop seems to be the IDE of choice for many C# programmers.


Thanks to so many people @UF for their very useful help, this FAQ wouldn't be the same without them. In particular, this thread is based on aks44's thread on C and C++ (see link in sticky). Not only is this thread based on it, it is blatently copying it, I hope he doesn't mind...

[Kadrus]

Good Thread,this will help a lot of windows c# programmers(new comers) and Linux users that want to learn c# and are facing problems compiling,setting up an environment,etc.
Well Done.

[LaRoza]

Good Thread,this will help a lot of windows c# programmers(new comers) and Linux users that want to learn c# and are facing problems compiling,setting up an environment,etc.
Well Done.

Thanks. You'll notice it is a rip off of the Java FAQ, which was a rip off of the C++ FAQ (which I didn't write).

I just changed a few names and commands, added a few sentences and it was done

[Kadrus]

Well still useful ,although I don't code with C# .But do some coding with F#.

[era86]

The compiler is your friend, the messages it outputs are kind advices rather than punishments. You should really take the time to try and understand those messages, this is a very good way to improve your code's quality.

Very well said. You should link to this in a sticky or sig.

[LaRoza]

Very well said. You should link to this in a sticky or sig.

I didn't actually write it: http://ubuntuforums.org/showthread.php?t=689635

[Can+~]

I'm not a C# expert, but:

//First C# Program
using System;

namespace Main
{ // <------ Where's the matching brace?
   class Welcome
   {
      public static void Main( string[] args )
      {
          Console.Write("Hello world\n");
      }
   } 

[LaRoza]

I'm not a C# expert, but:

Think you are clever, huh?

Adding brace and counter snipe comment

[Can+~]

Think you are clever, huh?

Adding brace and counter snipe comment

No, actually I know crap about C#. I even though that you left it open because it was part of the notation.

[LaRoza]

No, actually I know crap about C#. I even though that you left it open because it was part of the notation.

Think Java (if you don't know Java, think C++).

As for it being part of the notation, it is technically, but if you want it to compile you should close it.