Question

I am having dependency troubles. I have two classes: Graphic and Image. Each one has its own .cpp and .h files. I am declaring them as the following:

Graphic.h:

     #include 'Image.h'     class Image;     class Graphic {       ...     }; 

Image.h:

     #include 'Graphic.h'     class Graphic;     class Image : public Graphic {       ...     };

When I try to compile, I get the following error:

     Image.h:12: error: expected class-name before ‘{’ token 

If I remove the forward declaration of Graphic from Image.h I get the following error:

     Image.h:13: error: invalid use of incomplete type ‘struct Graphic’     Image.h:10: error: forward declaration of ‘struct Graphic’ 

Answer 1

This worked for me:

Image.h:

#ifndef IMAGE_H #define IMAGE_H  #include 'Graphic.h' class Image : public Graphic {  };  #endif 

Graphic.h:

#ifndef GRAPHIC_H #define GRAPHIC_H  #include 'Image.h'  class Graphic { };  #endif 

The following code compiles with no error:

#include 'Graphic.h'  int main() {   return 0; }