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Re: C++



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On Mon, 24 Feb 2003 10:20:45 -0600, Thomas Dodd wrote:

>  I had a question for a C++ programmer. Thought I might find one here :)
> 
> 
> I have 2 classes that need to reference each other.
> 
> "headerA.h"
> class A{
> public:
>    int x;
>    int y;
>    B *left;
>    B *right;
> }
> 
> "headerB.h"
> class B{
> public:
>    int a;
>    int b;
>    A *parent;
>    char foo();
> }
> 
> Give that top is of type A, in top.left.foo() I need to modify top.right.a
> 
> Any ideas? I've tried passing a A* in the constructor for B, but the 
> compiler doesn't
> realize that A is a class when I try to compile, and complains about no 
> type listed.
> 
> I seams to be a circular reference since A needs B and B needs A. This 
> cannot be that
> unusual, and has probably been solved before, I just don't know how.
> 
> Right now moy only though is to make parent a void* and the cast it to a 
> A* in the
> implementation of B. That removes all type checking though and I'd 
> rather not abuse
> void pointers like that.

Since only pointers to A and B are involved, a forward declaration

class A;

in front of class B and 

class B;

in front of class A should suffice.

- -- 
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