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:

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<?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());
  
?>

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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:

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<?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());
  
?>

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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



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