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From: rfg@ics.uci.edu (Ronald Guilmette)
Newsgroups: comp.lang.c++
Subject: Re: how do you define classes that refer to each other ???
Message-ID: <2605ECC2.24861@paris.ics.uci.edu>
Date: 20 Mar 90 08:41:39 GMT
References: <49689@wlbr.IMSD.CONTEL.COM>
Reply-To: rfg@ics.uci.edu (Ronald Guilmette)
Organization: UC Irvine Department of ICS
Lines: 60

In article <49689@wlbr.IMSD.CONTEL.COM> mh@awds26.UUCP (Mike Hoegeman) writes:
>
>This is probably a stupid question, but here goes anyway.  how do you
>set up two classes that refer to each other ?  Here's a simple example
>to demonstrate my problem.
>
>
>    class thing {
>	int data[5];
>	void execute(stack &s) {
>	    s.push(this);
>	}
>    }
>
>    class stack {
>	stack_store thing[500];
>	int si;
>    private:
>	void push(thing *t);
>	stack() {
>	    si = 0;
>	}
>    }
>
>    void
>    stack::push(thing *t) {
>	stack_store[si++] = *t;
>    }
>
>    main() {
>	thing mything;
>	stack mystack;
>
>	mything.execute();
>    }
>
>Now, the question is. How do I properly forward declare class 'stack'
>to class 'thing' so that everybody is happy ?

Declare:

	class stack;

before the declaration of class "thing".  Then move the body of the function
thing::execute out of the "thing" class declaration and put it after the
class declaration for class "stack".

>I have the stroustrup C++ book as well as the Dewhurst/Stark C++ book
>so an admonishing "you'll find this on page <n> in Stroustrup you
>moron" is fine :-). I've scanned through these two books but have not
>found the answer.

You'll find this on page <n> in Stroustrup you moron. :-)

(Sorry.  I couldn't resist. :-)


// Ron Guilmette (rfg@ics.uci.edu)
// C++ Entomologist
// Motto:  If it sticks, force it.  If it breaks, it needed replacing anyway.