operator==

template<class Key, class Pred, class A>
    bool operator==(
        const set <Key, Pred, A>& lhs,
        const set <Key, Pred, A>& rhs);
template<class Key, class Pred, class A>
    bool operator==(
        const multiset <Key, Pred, A>& lhs,
        const multiset <Key, Pred, A>& rhs);

The first template function overloads operator== to compare two objects of template class multiset. The second template function overloads operator== to compare two objects of template class multiset. Both functions return lhs.size() == rhs.size() && equal(lhs. begin(), lhs. end (), rhs.begin()).