Alvaro,

In addition to what others have said you can still define preprocessor constants in C# using any of the following, some of which do not exist in C/C++.

#if 
#else 
#elif 
#endif 
#define 
#undef 
#warning 
#error 
#line 
#region 
#endregion 

The C# compiler does not have a seperate preprocessor as in C/C++ so you don't have a #include available.

It also worth pointing out that you can have conditionally called void methods using the Conditional attribute.

#define DEBUG

using System;
using System.Diagnostics;

class SampleClass
{
   [Conditional("DEBUG")]
   public static void ConditionallyIncluded() {
      Console.WriteLine("Hello Zaphod!");
   }
}

Regards
Neil