The Ds\Deque::apply() function is an inbuilt function in PHP which is used to update the values of Deque by performing operations as defined by the callback function.
Syntax:
public Ds\Deque::apply( $callback ) : void
Parameters: This function accepts single parameter $callback which holds the function define the operation to be performed on each element of the Deque.
Return value: This function does not return any value.
Below programs illustrate the Ds\Deque::apply() function in PHP:
Program 1:
<?php   // Declare deque $deck = new \Ds\Deque([1, 2, 3, 4, 5, 6]);   echo("\nElements in the deque are\n");   // Display the deque elements print_r($deck);   // Use apply() function to implement // the operation $deck->apply(function($element) {     return $element * 10; });   echo("\nUpdated elements in the deque\n");   // Display the deque elements print_r($deck);   ?> |
Elements in the deque are
Ds\Deque Object
(
[0] => 1
[1] => 2
[2] => 3
[3] => 4
[4] => 5
[5] => 6
)
Updated elements in the deque
Ds\Deque Object
(
[0] => 10
[1] => 20
[2] => 30
[3] => 40
[4] => 50
[5] => 60
)
Program 2:
<?php   // Declare deque $deck = new \Ds\Deque([10, 20, 30, 40, 50, 60]);   echo("\nElements in the deque are\n");   // Display the deque elements print_r($deck);   // Use apply() function to implement // the operation $deck->apply(function($element) {     return $element % 10; });   echo("\nUpdated elements in the deque\n");   // Display the deque elements print_r($deck);   ?> |
Elements in the deque are
Ds\Deque Object
(
[0] => 10
[1] => 20
[2] => 30
[3] => 40
[4] => 50
[5] => 60
)
Updated elements in the deque
Ds\Deque Object
(
[0] => 0
[1] => 0
[2] => 0
[3] => 0
[4] => 0
[5] => 0
)
Reference: http://php.net/manual/en/ds-deque.apply.php
