# Iterators¶

Template classes concurrent_unordered_set and concurrent_unordered_multiset support forward iterators; that is, iterators that can advance only forwards across a table. Reverse iterators are not supported. Concurrent operations (count, find, insert) do not invalidate any existing iterators that point into the table. Note that an iterator obtained via begin() will no longer point to the first item if insert inserts an item before it. Erasure (unsafe_erase) does not invalidate iterators other than those pointing to erased elements.

Methods cbegin and cend follow C++11 conventions. They return const_iterator even if the object is non-const. The following table provides additional information on the members of this template class.

Member, Description

iterator begin()

Returns: iterator pointing to first item in the set.

const_iterator begin() const

Returns: const_iterator pointing to first item in the set.

iterator end()

Returns: iterator pointing to immediately past last item in the set.

const_iterator end() const

Returns: const_iterator pointing to immediately past last item in the set.

const_iterator cbegin() const

Returns: const_iterator pointing to the first item in the set.

const_iterator cend() const

Returns: const_iterator pointing to immediately after the last item in the set.