From:	Steve Chapel <schapel AT utilicom DOT com>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: Linking problems with overloading operator<<
Date:	Thu, 15 Oct 1998 15:16:05 -0700
Organization:	Utilicom, Inc.
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Message-ID:	<36267425.718995BD@utilicom.com>
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gamma wrote:
> 
> I am having problems linking files that have the insertion and
> extraction operators overloaded.... here is a little snippet of
> code...
> 
> //Golfer.h
> 
> #ifndef _GOLFER_H_
> #define _GOLFER_H_
> 
> #include <string>
> #include <iostream>
> using namespace std;
> 
> class Golfer
> {
>         friend ostream& operator<<(ostream&, const Golfer&);
>         friend istream& operator>>(istream&, Golfer&);
> .
> .
> .
> }
> 
> ostream& operator<<(ostream& gout, const Golfer& outGolfer)
> {
>         gout << outGolfer.PIT << "\t" << outGolfer.name << "\t" <<
> outGolfer.rank;
>         return gout;
> }
> .
> .
> .
> 
> #endif
> 
> This complies okay but returns these linker errors.
> 
> Error:  Golfer.o :  In fraction 'operator<<(ostream &, Golfer const
> &)':
> Error:  Golfer.cpp(.text+0x4): multiple definition of
> 'operator<<(ostream &, Golfer const &)'
> 
> Any help would be greatly appreciated
> Thanks
> Charlie Mac.

The line with "friend" in the class is a declaration. The code where you
supply the details of the function is a definition.
You want to put only declarations in header files and definitions in
.cpp files.
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