Question

Im having a little problem with classes.
Here is some of my code:

//GameMap.h
#ifndef GAMEMAP_H
#define GAMEMAP_H
#include "apath.h"

class GameMap
{
    /*class definition here*/
};

#endif

and

//apath.h
#ifndef APATH_H
#define APATH_H

class path
{
    //some code...
    void DoSomething(GameMap map);
    //rest of class body
};

#endif

I cant use GameMap in apath.h, when I try to include “GameMap.h in this file I get some stupid errors… I also tried to add class GameMap; before definition of path class. Nothing helped… I really need to use it here…
If needed I can post some more code.

Thanx for any replies!

Answer 1

You should use forward declaration of class GameMap in apath.h:

class GameMap; // forward declaration

class path
{
    //some code...
    void DoSomething(GameMap map);
    //rest of class body
};    

Check: When can I use a forward declaration?

In following example I use forward declaration of class A so that I’m able to declare function useA that uses it:

// file a.h
class A;
void useA(A a);

and then in main.cpp I have:

#include "a.h"

class A
{
public:
    void foo() { cout << "A"; }
};

void useA(A a)
{
    a.foo();
}

which is absolutely correct, since class A is already defined here.

Hope this helps.