PHP | Ds\Deque filter() Function

The Ds\Deque::filter() function is an inbuilt function in PHP which is used to filter out the elements from the deque based on the operation defined in the callback function.

Syntax:

public Ds\Deque::filter( $callback ) : Ds\Deque

Parameters: This function accepts single parameter $callback which is the callback function which contains the definition of filter to the elements from the deque.

Return Value: This function returns a new Deque which contains all the values for which callback returns True or all values that convert to True if a callback was not provided.

Below programs illustrate the Ds\Deque::filter() function in PHP:

Program 1:

<?php

// Creating a deque
$deque = new \Ds\Deque([1, 2, 3, 4, 5, 6]);

echo("Elements in the deque are\n");

print_r($deque);

// Use filter() function to filter
// the elements as per requirement
print_r($deque->filter(function($value) {
    return $value % 2 == 0;
}));

?>

Output:

Elements in the deque are
Ds\Deque Object
(
    [0] => 1
    [1] => 2
    [2] => 3
    [3] => 4
    [4] => 5
    [5] => 6
)
Ds\Deque Object
(
    [0] => 2
    [1] => 4
    [2] => 6
)

Program 2:

<?php

// Creating a deque
$deque = new \Ds\Deque([10, 20, 3, 40, 50, 6]);

echo("Elements in the deque are\n");

print_r($deque);

// Use filter() function to filter
// the elements as per requirement
print_r($deque->filter(function($value) {
    return $value % 10 != 0;
}));

?>

Output:

Elements in the deque are
Ds\Deque Object
(
    [0] => 10
    [1] => 20
    [2] => 3
    [3] => 40
    [4] => 50
    [5] => 6
)
Ds\Deque Object
(
    [0] => 3
    [1] => 6
)

Reference: http://php.net/manual/en/ds-deque.filter.php