26 Containers library [containers]

26.4 Associative containers [associative]

26.4.5 Class template multimap [multimap]

26.4.5.4 multimap specialized algorithms [multimap.special]

template<class Key, class T, class Compare, class Allocator> void swap(multimap<Key, T, Compare, Allocator>& x, multimap<Key, T, Compare, Allocator>& y) noexcept(noexcept(x.swap(y)));
Effects: As if by x.swap(y).