From: "Tonetheman" <agcolston AT buckman DOT com>
Newsgroups: comp.lang.c++,comp.os.msdos.djgpp
Subject: templated operator<< question
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Message-ID: <SuPU2.8517$XT1.392824@newse1.midsouth.rr.com>
Date: Mon, 26 Apr 1999 01:41:06 GMT
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To: djgpp AT delorie DOT com
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Reply-To: djgpp AT delorie DOT com

Does anyone have any ideas about what I am doing wrong in this code?

Basically I am trying to re-use the STL set and I am not having much luck
with the << operator. I have also listed the error listing that I get when
trying to compile this sample program. It looks like the compiler cannot
match the function signatures but from all I have read it looks right to
me... If this is important I am using Windows 98 and DJGPP.

Thanks for any information or pointers ahead of time.

Tony

#include <iostream>
#include <set>

using namespace std;

template <class A>
class sset : public set<A>
{
public:
  friend ostream& operator<<(const sset<A>& src, ostream &os);
};

template <class A>
ostream& operator<<(const sset<A>& src, ostream & os)
{
set<A>::iterator p = src.begin();
while(p!=src.end())
  {
  os << *p << " ";
  }
return os;
};

int main()
{

sset<int> testSet;
testSet.insert(10);

cout << testSet << endl;

return 0;
}

Error listing is below::

mkuu2.cpp:10: warning: friend declaration `class ostream & operator <<(const
class sset<A> &, class ostream &)'
mkuu2.cpp:10: warning:   will not be treated as a template instantiation
mkuu2.cpp:10: warning:   unless you compile with -fguiding-decls
mkuu2.cpp:10: warning:   or add <> after the function name
mkuu2.cpp: In function `int main()':
mkuu2.cpp:30: no match for `_IO_ostream_withassign & << sset<int> &'
d:/djgpp/lang/cxx/iostream.h:108: candidates are: ostream::operator
<<(streambuf *)
d:/djgpp/lang/cxx/iostream.h:107:                 ostream::operator <<(ios &
(*)(ios &))
d:/djgpp/lang/cxx/iostream.h:106:                 ostream::operator
<<(ostream & (*)(ostream &))
d:/djgpp/lang/cxx/iostream.h:104:                 ostream::operator <<(long
double)
d:/djgpp/lang/cxx/iostream.h:100:                 ostream::operator
<<(float)
d:/djgpp/lang/cxx/iostream.h:99:                 ostream::operator
<<(double)
d:/djgpp/lang/cxx/iostream.h:97:                 ostream::operator <<(bool)
d:/djgpp/lang/cxx/iostream.h:95:                 ostream::operator <<(short
unsigned int)
d:/djgpp/lang/cxx/iostream.h:94:                 ostream::operator <<(short
int)
d:/djgpp/lang/cxx/iostream.h:92:                 ostream::operator <<(long
long unsigned int)
d:/djgpp/lang/cxx/iostream.h:91:                 ostream::operator <<(long
long int)
d:/djgpp/lang/cxx/iostream.h:89:                 ostream::operator <<(long
unsigned int)
d:/djgpp/lang/cxx/iostream.h:88:                 ostream::operator <<(long
int)
d:/djgpp/lang/cxx/iostream.h:87:                 ostream::operator
<<(unsigned int)
d:/djgpp/lang/cxx/iostream.h:86:                 ostream::operator <<(int)
d:/djgpp/lang/cxx/iostream.h:85:                 ostream::operator <<(const
void *)
d:/djgpp/lang/cxx/iostream.h:84:                 ostream::operator <<(const
signed char *)
d:/djgpp/lang/cxx/iostream.h:82:                 ostream::operator <<(const
unsigned char *)
d:/djgpp/lang/cxx/iostream.h:80:                 ostream::operator <<(const
char *)
d:/djgpp/lang/cxx/iostream.h:79:                 ostream::operator <<(signed
char)
d:/djgpp/lang/cxx/iostream.h:78:                 ostream::operator
<<(unsigned char)
d:/djgpp/lang/cxx/iostream.h:77:                 ostream::operator <<(char)
mkuu2.cpp:10:                 operator <<(const sset<int> &, ostream &)