multiset.cpp

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#include <algorithm>   // for set_intersection(), set_union()
#include <iostream>    // for cout, endl, ostream
#include <iterator>    // for ostream_iterator
#include <sstream>     // for ostringstream
#include <set>         // for set
 
#include <examples.h>
 
 
typedef std::multiset<int, std::less<int>, std::allocator<int> > IntSet;
 
 
std::ostream& operator<< (std::ostream& out, const IntSet& s)
{
    std::ostringstream strm;
 
    typedef std::ostream_iterator<int, char, std::char_traits<char> >
        OstreamIter;
 
    std::copy (s.begin (), s.end (), OstreamIter (strm, " "));
 
    const std::ostream::sentry guard (out);
 
    if (guard) {
        const std::string data = strm.str ();
 
        if (   std::streamsize (data.size ())
            != out.rdbuf ()->sputn (data.data (), data.size ()))
            out.setstate (std::ios::badbit);
    }
 
    return out;
}
 
 
int main ()
{
    // Create a multiset of integers.
    IntSet  si;
 
    for (IntSet::value_type j = 0; j < 2; j++) {
        for (IntSet::value_type i = 0; i < 10; ++i)
            // Insert values with a hint.
            si.insert (si.begin (), i);
    }
 
    // Print out the multiset.
    std::cout << si << std::endl;
 
    // Make another multiset and an empty multiset.
    IntSet si2, result;
    for (IntSet::value_type i = 0; i < 10; i++)
        si2.insert (i + 5);
 
    std::cout << si2 << std::endl;
 
    // Try a couple of set algorithms.
    std::set_union (si.begin (), si.end (), si2.begin (), si2.end (),
                    std::inserter (result, result.begin ()));
 
    std::cout << "Union:\n" << result << std::endl;
 
    result.erase (result.begin (), result.end ());
 
    std::set_intersection (si.begin (), si.end (), si2.begin (), si2.end (),
                          std::inserter (result, result.begin ()));
 
    std::cout << "Intersection:\n" << result << std::endl;
 
    return 0;
}