#include <set>
#include <QDebug>

int main(int argc, char *argv[])
{

    std::set < int > setint;

    for ( unsigned i = 0; i < 20; ++i )
    {
        setint.insert (i);
    }

    for ( std::set<int>::const_iterator it = setint.begin(); it != setint.end(); ++it)
    {
        qDebug() << *it;
    }

    return 0;
}