Including Files

[The Hobo]

I'm trying to do something like this:

MainClass.h:

#ifndef __MAIN_CLASS_H
#define __MAIN_CLASS_H

#include "SecondaryClass.h"

class MainClass
{
	private:
		SecondaryClass *secondaryClass;
		
	public:
		MainClass();
		~MainClass();
	
};

#endif

SecondaryClass.h:

#ifndef __SECONDARY_CLASS_H
#define __SECONDARY_CLASS_H

#include "MainClass.h"

class SecondaryClass
{
	private:
		MainClass *m_mainClass;
		
	public:
		SecondaryClass( MainClass* );		
		~SecondaryClass();
};

#endif

And I get the following errors:

In file included from MainClass.h:4,
from main.cpp:2:
SecondaryClass.h:9: error: ISO C++ forbids declaration of `MainClass' with no type
SecondaryClass.h:9: error: expected `;' before '*' token

make.exe: *** [main.o] Error 1

I'm sure this is because I am including a file that includes the file I'm currently in.

The point of this being that MainClass has a member variable of Secondary class, which also has a reference to the MainClass that instantiated it.

Any ideas on how to accomplish this?

[Kal-El]

I think because never reashes to the end of the class...
See, is like this:
1) start header A.
2) header A calls header B.
3) start header B.
4) header B calls header A.
5) start header A.
6) header A calls header B, again!!!! why I didn't end the step 1 header A ?
...

Never reashes to the end of the class, because you are like inner loop or something the header over and over and over

[The Hobo]

I don't think that would be the case due to the #ifndef #endif block around the code. The class is only defined once -- the second time, the code in the block should be ignored. Correct?

[Kal-El]

Correct! But see this:
Even is "in used" the header, it never reashes the end of the header MainClass.

[The Hobo]

I have no idea what you are talking about.

[Kal-El]

And I don't why are you using this kinda code

[The Hobo]

Is there something wrong with it?

[chemicalNova]

I think what Kal-El means, is this:

#ifndef __MAIN_CLASS_H
#define __MAIN_CLASS_H
 
// #include "SecondaryClass.h"
 
class MainClass
{
    private:
        SecondaryClass *secondaryClass;
        
    public:
        MainClass();
        ~MainClass();
    
};
 
#include "SecondaryClass.h" // Put it here, because the preprocessor will know what MainClass is now..
 
#endif

Although, I'm not sure if that is correct.. I'll test it soon and get back to you.

chem

[The Hobo]

Chemical, I do not believe I can do that, because MainClass needs to have the definition of SecondaryClass.

[chemicalNova]

I've never tried something like this.. as I've never had the need to. What you might need, is a friend class to both of your current classes, which handles the information between the two.

I'll stuff around with your code for a bit and get back to you.

chem

[chemicalNova]

Actually.. silly me.

Just forward declare the classes:

MainClass.h

#ifndef __MAIN_CLASS_H
#define __MAIN_CLASS_H
 
#include "SecondaryClass.h"
 
class SecondaryClass; // <------
 
class MainClass
{
    private:
        SecondaryClass *secondaryClass;
        
    public:
        MainClass();
        ~MainClass();
    
};
 
#endif

SecondaryClass.h

#ifndef __SECONDARY_CLASS_H
#define __SECONDARY_CLASS_H
 
#include "MainClass.h"
 
class MainClass; // <--------
 
class SecondaryClass
{
    private:
        MainClass *m_mainClass;
        
    public:
        SecondaryClass( MainClass* );       
        ~SecondaryClass();
};
 
#endif

chem