The SplDoublyLinkedList::key() function is an inbuilt function in PHP which is used to return the index of the current node.
Syntax:
mixed SplDoublyLinkedList::key( void )
Parameters: This function does not accepts any parameters.
Return Value: It returns the index of current node.
Below programs illustrate the SplDoublyLinkedList::key() 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' );
$list -> rewind ();
// Use SplDoublyLinkedList::key() function // to get the key var_dump( $list ->key());
// Use next() function to increment // the index value $list ->next();
// Use SplDoublyLinkedList::key() function // to get the key var_dump( $list ->key());
?> |
Output:
int(0) int(1)
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);
$list -> rewind ();
// Use SplDoublyLinkedList::key() function // to get the key var_dump( $list ->key());
// Use next() function to increment // the index value $list ->next();
$list ->next();
$list ->next();
// Use SplDoublyLinkedList::key() function // to get the key var_dump( $list ->key());
?> |
Output:
int(0) int(3)
Reference: https://www.php.net/manual/en/spldoublylinkedlist.key.php