Re: mem_fun error

From:

"Victor Bazarov" <v.Abazarov@comAcast.net>

Newsgroups:

comp.lang.c++

Date:

Wed, 7 Mar 2007 17:10:28 -0500

Message-ID:

<esnd8k$lgh$1@news.datemas.de>

joseph cook wrote:

I am getting a compile error on any compiler I try, so I know I have
an error here. Can anyone see it?

//includes

class Foo
{
public:
Foo(int a){m_hi = a;}
int hi(){return m_hi;}

This is not a proper comparison function.

int m_hi;
};

int main()
{
std::vector<Foo *> data;
data.push_back(new Foo(3));

max_element(data.begin(),
data.end(),
std::mem_fun(&Foo::hi));

The third argument needs to be a comparison function with a very
specific signature. Think how your 'hi' should be used with TWO
arguments of type Foo*.

}

gives a compile error:
in gcc: stl_algo.h:4565: error: no match for call to
'(std::mem_fun_t<int, Foo>) (Foo*&,Foo*&)'
stl_function.h:600: note: candidates are: _Ret
std::mem_fun_t<_Ret,_Tp>::operator()(_Tp*) const [with _Ret = int,
_Tp = Foo]

help!

}

V
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