In computingthe [[C++ programming language]], '''unordered associative containers''' refer toare a group of class templates in the [[C++ Standard Library|standard library]] of the [[C++|C++ programming language]] that implement variations of [[hash table]]s. Being [[Template (programming)|templates]], they can be used to store arbitrary elements, such as integers or custom classes. The following containers are defined in the current revision of the C++ standard: <code>unordered_set</code>, <code>unordered_map</code>, <code>unordered_multiset</code>, <code>unordered_multimap</code>. Each of these containers differ only on constraints placed on their elements.
The unordered associative containers are similar to the [[Associative containers (C++)|associative containers]] in [[C++ standard library]] but have different constraints. As their name implies, the elements in the unordered associative containers are not [[well ordering|ordered]]. This is due to the use of hashing to store objects. The containers can still be [[iterator|iterated]] through like a regular associative container.
