Forward Declaration of Class, Function

Question

When forward declarations of functions work in a source file (.cpp), why would the same doesn\'t work for classes ?

Thanks.

// main.cpp

void forwar         


        

Answer 1

The forward declaration class One; allows you to refer to the class itself but not to any of its members. You have to put all definitions of class members after the full declaration of the class. (Or inside, of course.)