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Two-way class communication

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Join Date: Mar 2005

Posts: 10

Reputation: j.kelly is an unknown quantity at this point

Solved Threads: 0

j.kelly

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Newbie Poster

Two-way class communication

Mar 20th, 2005

I'm pretty new to C++ and I'm having a problem with a Uni coursework.

I have two classes A & B which need to be able to call each others functions so they each hold a pointer to the other.

I had the problem that they #included each other so I was getting an include recursion, which I solved by using forward referencing.

Now I have the problem that because I used forward referencing when I come to implement a function to use that pointer I am told that the class whose pointer I want to use is not defined.

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
function implementation:
 
void A::MyFunction()
{
    this->pointer->MyFunction();
}
 
 
headers:
 
class B;
class A
{
public:
    A(B* aPointer);
    ~A(void);
    void MyFunction();
private:
    B* pointer;
};
 
class A;
class B
{
public:
    B(A* aPointer);
    ~B(void);
    void MyFunction();
private:
    A* pointer;
};
function implementation:

void A::MyFunction()
{
    this->pointer->MyFunction();
}


headers:

class B;
class A
{
public:
    A(B* aPointer);
    ~A(void);
    void MyFunction();
private:
    B* pointer;
};

class A;
class B
{
public:
    B(A* aPointer);
    ~B(void);
    void MyFunction();
private:
    A* pointer;
};

I've given this A & B example just to simplify the problem I'm having.

Thanks,
James

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Join Date: Mar 2005

Posts: 10

Reputation: j.kelly is an unknown quantity at this point

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j.kelly

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Newbie Poster

Re: Two-way class communication

Mar 20th, 2005

Didn't realise I could just #include the other class header into the .cpp file instead of the .h file.

Problem solved.

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Join Date: Dec 2004

Posts: 445

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1o0oBhP

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Posting Pro in Training

Re: Two-way class communication

Mar 20th, 2005

Another way might be to define two classes with everything private (-constructors) and put the other classes functions as friends? the use of the static keyword could help as static fields dont require objects to be created (they can be used like 'constants' in effect)

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