24 Containers library [containers]

24.4 Associative containers [associative]

24.4.7 Class template multiset [multiset]

24.4.7.3 Erasure [multiset.erasure]

template<class Key, class Compare, class Allocator, class Predicate> typename multiset<Key, Compare, Allocator>::size_type erase_if(multiset<Key, Compare, Allocator>& c, Predicate pred);
Effects: Equivalent to: auto original_size = c.size(); for (auto i = c.begin(), last = c.end(); i != last; ) { if (pred(*i)) { i = c.erase(i); } else { ++i; } } return original_size - c.size();