How can I compile .NET 3.5 C# code on a system without Visual Studio?

Question

I have some C# code that uses some constructs specific to .NET 3.5. When you install the .NET Framework distribution, you get the C# compiler installed with it (csc.exe). Even if I specify the csc.exe in C:\Windows\Microsoft.NET\Framework\v3.5, I cannot compile the code on a computer with only the .NET Framework installed, but not Visual Studio. I am able to compile code that uses v2.0 constructs without difficulty. How can I accomplish this?

Here is a sample that demonstrates my problem:

using System;
class Program
{
    public static void Main()
    {
        // The MacOSX value to the PlatformID enum was added after
        // .NET v2.0
        if (Environment.OSVersion.Platform == PlatformID.MacOSX)
        {
            Console.WriteLine("Found mac");
        }
        Console.WriteLine("Simple program");
    }
}

When compiling this code using csc.exe, I receive the following error:

test.cs(9, 58): error CS0117: 'System.PlatformID' does not contain a definition for 'MacOSX'

When executing csc.exe /? I receive the banner:

Microsoft (R) Visual C# 2008 Compiler version 3.5.21022.8
for Microsoft (R) .NET Framework version 3.5
Copyright (C) Microsoft Corporation. All rights reserved.

It should be fine to compile things without Visual Studio. Could you give an example of what you're trying to compile and what errors you're getting? Without that information we're working blind... — Jon Skeet
It would be helpful if you could expand on "I cannot compile the code on a computer with only the .NET Framework installed", what errors does csc return? — Rob
What is the version when you just type csc.exe ? Is it showing a 3.5.* version of the compiler or 2.0? — Robaticus
As a side note, if can't install VisualStudio because it's expensive but you can install an IDE, have a look at: SharpDevelop — digEmAll

Hans Passant Hans Passant · Accepted Answer · 2011-02-17T15:18:45

Microsoft (R) Visual C# 2008 Compiler version 3.5.21022.8

That's old, original .NET 3.5 release. Service Pack 1 has a rather unfortunate name, there were a great many changes. I don't have the time machine to check if it added the MacOSX member. Timing is about right for coinciding with Silverlight.

Enable Windows Update or install SP1 directly.

How can I compile .NET 3.5 C# code on a system without Visual Studio?

4 Answers