Multiset

A multiset container works in a manner similar to a set container, except for the fact that a set allows only unique values to be stored whereas a multiset lets you store duplicate values. As you know, in the case of set and multiset containers, the values themselves are used as keys to organize the data. A multiset container is just like a set; it doesn't allow modifying the values stored in the multiset.

Let's write a simple program using a multiset:

#include <iostream>
#include <set>
#include <iterator>
#include <algorithm>
using namespace std;

int main() {
  multiset<int> s = { 10, 30, 10, 50, 70, 90 };

  cout << "\nMultiset values are ..." << endl;

  copy ( s.begin(), s.end(), ostream_iterator<int> ( cout, "\t" ) );
  cout << endl;

  return 0;
}

The output can be viewed with the following command:

./a.out

The output of the program is as follows:

Multiset values are ...
10 30 10 50 70 90

Interestingly, in the preceding output, you can see that the multiset holds duplicate values.