Search results
Results from the WOW.Com Content Network
In computer science, a multimap (sometimes also multihash, multidict or multidictionary) is a generalization of a map or associative array abstract data type in which more than one value may be associated with and returned for a given key. Both map and multimap are particular cases of containers (for example, see C++ Standard Template Library ...
The operations that are usually defined for an associative array are: [3] [4] [8] Insert or put add a new (,) pair to the collection, mapping the key to its new value. Any existing mapping is overwritten. The arguments to this operation are the key and the value. Remove or delete
An object is similar to a map—both let you set keys to values, retrieve those values, delete keys, and detect whether a value is stored at a key. For this reason (and because there were no built-in alternatives), objects historically have been used as maps.
In JavaScript, an "object" is a mutable collection of key-value pairs (called "properties"), where each key is either a string or a guaranteed-unique "symbol"; any other value, when used as a key, is first coerced to a string. Aside from the seven "primitive" data types, every value in JavaScript is an object. [49]
Single-value containers store each object independently. Objects may be accessed directly, by a language loop construct (e.g. for loop) or with an iterator. An associative container uses an associative array, map, or dictionary, composed of key-value pairs, such that each key appears at most once in the container. The key is used to find the ...
Map functions can be and often are defined in terms of a fold such as foldr, which means one can do a map-fold fusion: foldr f z . map g is equivalent to foldr (f . g) z. The implementation of map above on singly linked lists is not tail-recursive, so it may build up a lot of frames on the stack when called with a large list. Many languages ...
BSON represents both arrays and maps internally as documents, which are maps, where an array is a map with keys as decimal strings counting up from 0. MessagePack on the other hand represents both maps and arrays as arrays, where each map key-value pair is contiguous, making odd items keys and even items values.
Maps are data structures that associate a key with an element. This lets the map be very flexible. If the key is the hash code of the element, the Map is essentially a Set. If it's just an increasing number, it becomes a list. Examples of Map implementations include java.util.HashMap, java.util.LinkedHashMap, and java.util.TreeMap.