Questions tagged
A dictionary maps keys to values allowing efficient retrieval of values by keys. USE [map-function] TAG for mapping functions; and for geography, [maps].

A dictionary (also known as map, associative array, or symbol table) in computer science is a data structure that maps keys to values such that given a key its corresponding value can be efficiently retrieved.

It is commonly implemented as a hash map which allow O(1) amortized lookup. Alternatively, they may be implemented as a sorted list, with lookup requiring a binary search and making the lookup O(log N) amortized instead.

When tagging a question with dictionary, be sure to tag it with the language being used as well.

In C++

std::map<Key, T, Compare, Allocator>: A sorted associative container that contains key-value pairs with unique keys.


Dictionary<TKey, TValue>: Represents a collection of keys and values.

In Python

dict: Maps hashable keys to arbitrary objects.

In Java

Map<K, V>: An object that maps keys to values.

See also

Related tags: associative-array, unordered-map, multimap, treemap, hashmap, hashtable, lua-table

For questions about Mapping Functions over collections of data, use map-function tag.

For questions about the Geographical maps i.e. for visual representation of area, please use maps tag