Syntax:

    #include <set>
    multiset& operator=(const multiset& c2);
    bool operator==(const multiset& c1, const multiset& c2);
    bool operator!=(const multiset& c1, const multiset& c2);
    bool operator<(const multiset& c1, const multiset& c2);
    bool operator>(const multiset& c1, const multiset& c2);
    bool operator<=(const multiset& c1, const multiset& c2);
    bool operator>=(const multiset& c1, const multiset& c2);

All of the C++ containers can be compared and assigned with the standard comparison operators: ==, !=, ⇐, >=, <, >, and =. Performing a comparison or assigning one multiset to another takes linear time.

Two multisets are equal if:

1. Their size is the same, and
2. Each member in location i in one multiset is equal to the member in location i in the other multiset.

Comparisons among multisets are done lexicographically.