PHP SplDoublyLinkedList unshift() Function

0 0 1 minute read

The SplDoublyLinkedList::unshift() function is an inbuilt function in PHP which is used to add the element at the beginning of a doubly linked list.

Syntax:

void SplDoublyLinkedList::unshift( $value )

Parameters: This function accepts a single parameter $value which is used to unshift the value in a doubly linked list.

Return Value: It does not return any value.

Below programs illustrate the SplDoublyLinkedList::unshift() function in PHP:

Program 1:

<?php  
  
// Declare an empty SplDoublyLinkedList 
$list = new \SplDoublyLinkedList; 
  
// Use SplDoublyLinkedList::add() function to  
// add elements to the SplDoublyLinkedList 
$list->add(0, 30); 
$list->add(1, 20); 
$list->add(2, 30); 
$list->add(3, "Geeks"); 
$list->add(4, 'G'); 
  
// Use unshift() function 
$list->unshift("zambiatek"); 
  
// Display the list elements 
print_r($list); 
  
?>  

Output:

SplDoublyLinkedList Object
(
    [flags:SplDoublyLinkedList:private] => 0
    [dllist:SplDoublyLinkedList:private] => Array
        (
            [0] => zambiatek
            [1] => 30
            [2] => 20
            [3] => 30
            [4] => Geeks
            [5] => G
        )

)

Program 2:

<?php  
  
// Declare an empty SplDoublyLinkedList 
$list = new \SplDoublyLinkedList(); 
  
// Use SplDoublyLinkedList::push() function to  
// add elements to the SplDoublyLinkedList 
$list->push(1); 
$list->push(2); 
$list->push(3); 
$list->push(8); 
$list->push(5); 
  
// Use unshift() function 
$list->unshift("Geeks"); 
  
// Display the list elements 
print_r($list); 
  
?>  

Output:

SplDoublyLinkedList Object
(
    [flags:SplDoublyLinkedList:private] => 0
    [dllist:SplDoublyLinkedList:private] => Array
        (
            [0] => Geeks
            [1] => 1
            [2] => 2
            [3] => 3
            [4] => 8
            [5] => 5
        )

)

Reference: https://www.php.net/manual/en/spldoublylinkedlist.unshift.php