Compiler Error CS1517

  • Article

Invalid preprocessor expression

The compiler encountered an invalid preprocessor expression.

For more information, see Preprocessor Directives.

The following sample shows some valid and invalid preprocessor expressions:

// CS1517.cs
#if symbol      // OK
#endif
#if !symbol     // OK
#endif
#if (symbol)    // OK
#endif
#if true        // OK
#endif
#if false       // OK
#endif
#if 1           // CS1517
#endif
#if ~symbol     // CS1517
#endif
#if *           // CS1517
#endif

class x
{
   public static void Main()
   {
   }
}