The string class is implemented as basic_string<char> which makes it a random access container and a sequence. Since a random access container is a refinement of a reversible container which in turn is a refinement of a forward container, its iterators may be forward, bidirectional, or random-access. Since strings are also assignable, default constructible, equality comparable, and less-than comparable, one may apply a wide variety of algorithms to them. However, to simplify its use, the string class implements a large number of the standard algorithms as member functions.