Help declaring two classes dependent on eachother.

[Bobruisk]

Hi!

I have a problem regarding two classes that are dependent on eachother in their definition. What I'm trying to acomplish is the following;

A.h:

#include "B.h"

class A
{
private:
    /* a bunch of functions and varibles here */
    int F1();
    int F2();
    ...
    
    friend int B::Func(A*);
}

B.h:

class A;

class B
{
    int Func(A*);
}

B.cpp:

#include "B.h"

int B::Func(A*)
{
    return(A->F1() + A->F2())
}

The problem is that B only knows that there is a class called A, but it does not know what it contains (F1, F2 ...). I cannot use class A before it's defined. How do i get around this problem? I cannot include A.h in B.h because either way I put it, either

A.h asks: What is class B?

or

B.h asks: What is class A?

I hope I've made my problem understood, ask if clarification is needed somewhere.

Thanks!

-Bobruisk

[kev82]

make b.cpp include a.h

You will need to add include guards to stop b.h being included twice.

[ModShop]

AND, move any code from the header files (from one class involving the other at least) into the source files where both class definitions will be visible.

[kbw]

I compiled your stuff. I assume you didn't attempt to compile exactly what you posted as there are clear problems.

Anyway, it compiled with the obvious fixes:
A.h

#pragma once
#include "B.h"

class A
{
private:
    /* a bunch of functions and varibles here */
    int F1();
    int F2();
    //...
    
    friend int B::Func(A*);
};

B.h

#pragma once
class A;

class B
{
public:
    int Func(A*);
};

B.cpp

#include "B.h"
#include "A.h"

int B::Func(A* a)
{
    return a->F1() + a->F2();
}

[kev82]

Just to point out that pragma once is non-standard, whereas include guards will always work.

[kbw]

Just to point out that pragma once is non-standard

True, and it's not recomended for good reason. But I just wanted to get the thing to compile with minimum fuss.

[anonymous23323124]

not recomended for good reason

What reason?

I usually do this:

#pragma once
#ifndef BLAH_HPP
#define BLAH_HPP
...
#endif 

so that I have the portability of the include guards and the possible compile time speed improvement, etc. of the pragma approach.

[Bobruisk]

Sorry, I missed to input the include guards. They are there already. I'm coding on a computer without network access so I had to type it in manually here.

The problem was that I forgot to include the A.h file in B.cpp file, which left B.cpp without the complete A-class definition.

Thanks for your help!
-Bobruisk