make_pair with auto_ptr: ... discards qualifiers

[Markus Dehmann]

I am trying to make a pair with a string and an auto_ptr:

#include <iostream>
#include <map>
using namespace std;

int main(){
auto_ptr<intp(n ew int(3));
make_pair("x",p );
}

But it won't compile:

stl_pair.h:85: error: passing `const std::auto_ptr<i nt>' as `t\
his' argument of `std::auto_ptr< _Tp>::operator
std::auto_ptr_r ef<_Tp1>() [with _Tp1 = int, _Tp = int]' discards
qualifiers

I didn't make p const, so I don't understand why it complains ... How
can I make it work?

[Victor Bazarov]

Markus Dehmann wrote:

I am trying to make a pair with a string and an auto_ptr:

#include <iostream>
#include <map>
using namespace std;

int main(){
auto_ptr<intp(n ew int(3));
make_pair("x",p );
}

But it won't compile:

stl_pair.h:85: error: passing `const std::auto_ptr<i nt>' as `t\
his' argument of `std::auto_ptr< _Tp>::operator
std::auto_ptr_r ef<_Tp1>() [with _Tp1 = int, _Tp = int]' discards
qualifiers

I didn't make p const, so I don't understand why it complains ... How
can I make it work?

You can't make it work. 'std::pair's constructor takes arguments by
const ref. Inside it constructs the members using copy-construction.
'std::auto_ptr' constructor takes non-const ref as its argument.

V
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[Daniel T.]

In article <11************ **********@i42g 2000cwa.googleg roups.com>,
"Markus Dehmann" <ma************ @gmail.comwrote :

I am trying to make a pair with a string and an auto_ptr:

#include <iostream>
#include <map>
using namespace std;

int main(){
auto_ptr<intp(n ew int(3));
make_pair("x",p );
}

But it won't compile:

stl_pair.h:85: error: passing `const std::auto_ptr<i nt>' as `t\
his' argument of `std::auto_ptr< _Tp>::operator
std::auto_ptr_r ef<_Tp1>() [with _Tp1 = int, _Tp = int]' discards
qualifiers

I didn't make p const, so I don't understand why it complains ... How
can I make it work?

Items in a pair must have standard copy and assignment semantics, and
auto_ptr doesn't.