PHP | Ds\Deque first() Function

The Ds\Deque::first() function is an inbuilt function in PHP which returns the first value in the Deque if Deque is not empty.

Syntax:

public Ds\Deque::first( void ) : mixed

Parameters: This function does not accept any parameter.

Return Value: This function returns the first element from the Deque, if the deque is not empty.

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

Program 1:

<?php

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

echo("Elements in the Deque\n");

// Display the Deque elements
print_r($deck);

echo("\nFirst element in the deque: ");

// Use first() function to find
// first element in the deque
var_dump($deck->first());

?>

Output:

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

First element in the deque: int(10)

Program 2:

<?php

// Declare a deque
$deck = new \Ds\Deque(["Geeks", "for", "GFG"]);

echo("Elements in the Deque\n");

// Display the Deque elements
print_r($deck);

echo("\nFirst element in the deque: ");

// Use first() function to find
// first element in the deque
var_dump($deck->first());

?>

Output:

Elements in the Deque
Ds\Deque Object
(
    [0] => Geeks
    [1] => for
    [2] => GFG
)

First element in the deque: string(5) "Geeks"

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