(PHP 5 >= 5.0.0, PHP 7) Returns the value at the specified index

(PHP 5 >= 5.0.0, PHP 7) Appends the value

(PHP 5 >= 5.2.0, PHP 7) Sort the entries with a user-defined comparison function and maintain key association

(PHP 5 >= 5.3.0, PHP 7) Constructs a new queue implemented using a doubly linked list

(PHP 5 >= 5.1.0, PHP 7) Notify an observer

(PHP 5 >= 5.1.0, PHP 7) Receive update from subject

(PHP 5 >= 5.3.0, PHP 7) Constructs a new empty queue

(PHP 5 >= 5.3.0, PHP 7) Check whether the doubly linked list contains more nodes

(PHP 5 >= 5.3.0, PHP 7) Extracts a node from top of the heap and sift up.

(PHP 5 >= 5.1.0, PHP 7) Get maximum line length