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find the value (if any) that is bound to a given key. The argument to this operation is the key, and the value is returned from the operation. If no value is found, some lookup functions raise an exception, while others return a default value (such as zero, null, or a specific value passed to the constructor).
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 value, the object, if it is stored in the container.
A vector-valued function, also referred to as a vector function, is a mathematical function of one or more variables whose range is a set of multidimensional vectors or infinite-dimensional vectors. The input of a vector-valued function could be a scalar or a vector (that is, the dimension of the domain could be 1 or greater than 1); the ...
Aside from the seven "primitive" data types, every value in JavaScript is an object. [50] ECMAScript 2015 also added the Map data structure, which accepts arbitrary values as keys. [51] C++11 includes unordered_map in its standard library for storing keys and values of arbitrary types. [52] Go's built-in map implements a hash table in the form ...
In computer programming, foreach loop (or for-each loop) is a control flow statement for traversing items in a collection. foreach is usually used in place of a standard for loop statement.
In JavaScript, an object is an associative array, augmented with a prototype (see below); each key provides the name for an object property, and there are two syntactical ways to specify such a name: dot notation (obj.x = 10) and bracket notation (obj["x"] = 10). A property may be added, rebound, or deleted at run-time.
In JavaScript an object is a mapping from property names to values—that is, an associative array with one caveat: the keys of an object must be either a string or a symbol (native objects and primitives implicitly converted to a string keys are allowed).
Elements of a newly created array may have undefined values (as in C), or may be defined to have a specific "default" value such as 0 or a null pointer (as in Java). In C++ a std::vector object supports the store, select, and append operations with the performance characteristics discussed above. Vectors can be queried for their size and can be ...