This documentation is archived and is not being maintained.

Compiler Error CS1517

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()
   {
   }
}
Show: