Re: STL - erasing from a set

From:
James Kanze <james.kanze@gmail.com>
Newsgroups:
comp.lang.c++.moderated,comp.lang.c++
Date:
Fri, 19 Nov 2010 14:03:32 CST
Message-ID:
<14a62694-d36c-4eb1-bf42-05f3658a5bab@m35g2000vbn.googlegroups.com>
On Nov 19, 7:14 am, Andrey <akr...@gmail.com> wrote:

You said,

This basically means you would need a
temporary container and it does not remove the mentioned elements from
the source set.


I understand that, but the problem is that this temporary container
cannot be a new (empty) set... it needs to be something that is filled
to the necessary capacity already.


Just the opposite, really. If the target container is a set, it
should be empty. IIRC, someone has already posted the correct
solution: use an insertion iterator for the output, e.g.:

I wrote another sample program to
see if I could I could get set_symmetric_difference to work:

#include <iostream>
#include <cstdlib>
#include <set>
#include <vector>
#include <algorithm>

using namespace std;

int main() {

    set<int> set_int;
    set_int.insert(2);
    set_int.insert(1);
    set_int.insert(3);

    set<int> set2_int;
    set2_int.insert(2);

    set<int> set_diff;

    set_symmetric_difference(set_int.begin(), set_int.end(),
set2_int.begin(), set2_int.end(), set_diff.begin());


    set_symmetric_difference(set_int.begin(), set_int.end(),
                             set2_int.begin(), set2_int.end(),
                             std::inserter(set_diff,
set_diff.begin()));

    return 0;
}


--
James Kanze

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