Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cornell!uw-beaver!tektronix!reed!psu-cs!karenc
From: karenc@psu-cs.UUCP (Karen Cunningham)
Newsgroups: comp.lang.c++
Subject: Problem with member functions as friends
Message-ID: <1623@psu-cs.UUCP>
Date: 8 Feb 89 18:55:19 GMT
Distribution: usa
Organization: Dept. of Computer Science, Portland State University; Portland OR
Lines: 65

I am teaching an object-oriented programming class in which I'm
including a section on c++.  I wanted to show several different
ways of allowing (selected parts of) a derived class access to private
data of the base class.  I succeeded in making several examples work,
but had trouble with one.  I tried to make a member function of the
derived class a friend of the base class.  This seems to be the same
as the example from page 195 in Stroustrup.  I tried to compile that
example (it is included below) on several different c++ compilers
without success.  The message I get occurs at the last line of class
employee and states that class manager is undefined.

Is this a bug or am I missing something?

Karen Cunningham

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              Portland State University; P.O. Box 751; Portland, OR  97207
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------------------------------Example Follows---------------------------
#include <stream.h>

class manager;

//  This is the example from Stroustrup, page 195.
//  The second example works (making class manager a friend), 
//  however the first example does not work (making function
//  "void manager::print" a friend).
//
//  I've tried defining a forward reference to manager::print,
//  and then making it a friend to employee that didn't work either.

class employee {
friend void manager::print(); // making this "friend class manager;" works 
	char* name;
	// ...
public:
	employee* next;
	employee(char* s) {name = s;}
	void print()	{cout << " employee name is "<< name << "\n";}
	// ...
};

class manager : public employee {
	// ...
public:
	manager(char* s) : (s) {;}
	void print();
	// ...
};

void manager::print()
{
	cout << " manager name is " << name << "\n";
	// ...
}

main() {
	manager mgr("Hugh");

	mgr.print();
}