# Iterators¶

The template classes concurrent_unordered_map and concurrent_unordered_multimap 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 map.

const_iterator begin() const

Returns: const_iterator pointing to first item in the map.

iterator end()

Returns

iterator pointing to immediately past last item in the map.

const_iterator end() const

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

const_iterator cbegin() const

Returns: const_iterator pointing to first item in the map.

const_iterator cend() const

Returns

const_iterator pointing to immediately after the last item in the map.