Re: map as associative array destroy object twice

From:

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

Newsgroups:

comp.lang.c++

Date:

Wed, 14 Feb 2007 16:25:46 -0500

Message-ID:

<eqvuoq$7gk$1@news.datemas.de>

semkin55@gmail.com wrote:

Here is a small program, that traces construction and distruction of
class A objects.
If I use make_pair to insert in a map everything is OK.
If I insert using [], than objects with index 11, 7 and 3 will be
deleted twice and objects with indexes 10, 6 and 2 not deleted at all.
What is wrong ? I am new to standard library.

I use Sun Studio 10: C++ 5.7 Compiler

#include <map>
#include <iostream.h>

There is no <iostream.h>

#include <iostream>

and you don't have the necessary <string>:

#include <string>

using namespace std;

class A
{
public:
A() : i(0)
{
   j = k++;
   cout << "Con " << i << " " << j << "\n";
};

A(int l) : i(l)
{
   j = k++;
   cout << "Con_k " << i << " " << j << "\n";
};

~A()
{
   cout << "Dest " << i << " " << j << "\n";
};

A(const A& a)
{
   i = a.i;
   j = k++;
   cout << "Copy " << i << " " << j << "\n";
};

Add here:

    A& operator=(const A& a)
    {
        cout << "Was " << i << ' ' << j << " -- now ";
        i = a.i;
        j = a.j;
        cout << i << " " << j << "\n";
        return *this;
    }

int i;
int j;
static int k;
};

int A::k = 0;

int main()
{
    cout << "1\n";
    std::string s;
    std::map<std::string, A> mp;

    cout << "2\n";
    s = "A";
    mp[s] = A(1);
    //mp.insert(make_pair(s, A(1)));

    cout << "3\n";
    s = "B";
    //mp.insert(make_pair(s, A(2)));
    mp[s] = A(2);

    cout << "4\n";
    s = "C";
    mp[s] = A(3);
    //mp.insert(make_pair(s, A(3)));

    cout << "5\n";
}

V
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