Compiler Error CS1554

Declaration is not valid; use '<type> operator op (...' instead

The return type for a user-defined operator must appear before the keyword operator.

The following sample generates CS1554:

// CS1554.cs
class MyClass
{
   public static operator ++ MyClass (MyClass f)    // CS1554
   // try the following line instead
   // public static MyClass operator ++ (MyClass f)
   {
      return new MyClass ();
   }

   public static void Main()
   {
   }
}