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The arrays are heterogeneous: a single array can have keys of different types. PHP's associative arrays can be used to represent trees, lists, stacks, queues, and other common data structures not built into PHP. An associative array can be declared using the following syntax:
In computer science, an associative array, map, symbol table, or dictionary is an abstract data type that stores a collection of (key, value) pairs, such that each possible key appears at most once in the collection. In mathematical terms, an associative array is a function with finite domain. [1] It supports 'lookup', 'remove', and 'insert ...
It is also possible to delete a key from an association list, by scanning the list to find each occurrence of the key and splicing the nodes containing the key out of the list. [1] The scan should continue to the end of the list, even when the key is found, in case the same key may have been inserted multiple times.
The principal benefit of a linked list over a conventional array is that the list elements can be easily inserted or removed without reallocation or reorganization of the entire structure because the data items do not need to be stored contiguously in memory or on disk, while restructuring an array at run-time is a much more expensive operation ...
[6] [7] The heap array is assumed to have its first element at index 1. // Push a new item to a (max) heap and then extract the root of the resulting heap. // heap: an array representing the heap, indexed at 1 // item: an element to insert // Returns the greater of the two between item and the root of heap.
Python dictionaries (a form of associative array) can also be directly iterated over, when the dictionary keys are returned; or the items() method of a dictionary can be iterated over where it yields corresponding key,value pairs as a tuple:
A stack can be easily implemented either through an array or a linked list, as it is merely a special case of a list. [19] In either case, what identifies the data structure as a stack is not the implementation but the interface: the user is only allowed to pop or push items onto the array or linked list, with few other helper operations.
In computer science, a dynamic array, growable array, resizable array, dynamic table, mutable array, or array list is a random access, variable-size list data structure that allows elements to be added or removed. It is supplied with standard libraries in many modern mainstream programming languages.