define OS constant for compilation : Undef : Preprocessing Directives C# Examples

    
#define  win2000
#define  release
#undef  win98  

using  System;
using  System.Diagnostics;

class  MainClass
{
        [Conditional("DEBUG")]
        public  static  void  DumpState()
        {
                Console.WriteLine("Dump  some  state...");
        }
        public  static  void  Main()
        {
              string  platformName;
              #if  winXP                  //Compiling  for  Windows  XP
                      platformName  =  "Microsoft  Windows  XP";
              #elif  win2000          //  Compiling  for  Windows  2000
                      platformName  =  "Microsoft  Windows  2000";
              #elif  winNT              //  Compiling  for  Windows  NT
                      platformName  =  "Microsoft  Windows  NT";
              #elif  win98              //  Compiling  for  Windows  98
                      platformName  =  "Microsoft  Windows  98";
              #else                            //  Unknown  platform  specified
                      platformName  =  "Unknown";
              #endif
              Console.WriteLine(platformName);
              //  Call  the  conditional  DumpState  method
              DumpState();
        }
}