Does PHP have built-in data structures?

Question

I'm looking at the PHP Manual, and I'm not seeing a section on data structures that most languages have, such as lists and sets. Am I just blind or does PHP not have anything like this built in?

Answer 1

The only native data structure in PHP is array. Fortunately, arrays are quite flexible and can be used as hash tables as well.

http://www.php.net/array

However, there is SPL which is sort of a clone of C++ STL.

http://www.php.net/manual/en/book.spl.php

Answer 2

PHP offers data structures through the Standard PHP Library (SPL) basic extension, which is available and compiled by default in PHP 5.0.0.

The data structures offered are available with PHP 5 >= 5.3.0, and includes:

Doubly Linked Lists

A Doubly Linked List (DLL) is a list of nodes linked in both directions to each others. Iterator’s operations, access to both ends, addition or removal of nodes have a cost of O(1) when the underlying structure is a DLL. It hence provides a decent implementation for stacks and queues.

• SplDoublyLinkedList class
  • SplStack class
  • SplQueue class

Heaps

Heaps are tree-like structures that follow the heap-property: each node is greater than or equal to its children, when compared using the implemented compare method which is global to the heap.

• SplHeap class
  • SplMaxHeap class
  • SplMinHeap class
• SplPriorityQueue class

Arrays

Arrays are structures that store the data in a continuous way, accessible via indexes. Don’t confuse them with PHP arrays: PHP arrays are in fact implemented as ordered hashtables.

• SplFixedArray class

Map

A map is a datastructure holding key-value pairs. PHP arrays can be seen as maps from integers/strings to values. SPL provides a map from objects to data. This map can also be used as an object set.

• SplObjectStorage class

Source: http://php.net/manual/en/spl.datastructures.php