The SplDoublyLinkedList::valid() function is an inbuilt function in PHP which is used to check whether the doubly linked list contains more nodes or not.
Syntax:
bool SplDoublyLinkedList::valid( void )
Parameters: This function does not accept any parameters.
Return Value: This function returns TRUE if the doubly linked list contains any more nodes and FALSE otherwise.
Below programs illustrate the SplDoublyLinkedList::valid() function in PHP:
Program 1:
<?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 ();
for ( $i = 0; $i < 5; $i ++) {
if ( $list ->valid())
echo $list ->current() . " " ;
$list ->next();
} ?> |
Output:
1 2 3 8 5
Program 2:
<?php // Declare an empty SplDoublyLinkedList $list = new SplDoublyLinkedList();
// Use SplDoublyLinkedList::add() function // to add the element into the list $list ->add(0, "Welcome" );
$list ->add(1, "to" );
$list ->add(2, "GeeksforGeeks" );
$list ->add(3, "A" );
$list ->add(4, 'Computer' );
$list ->add(5, "Science" );
$list ->add(6, 'Portal' );
$list -> rewind ();
for ( $i = 0; $i < 7; $i ++) {
if ( $list ->valid())
echo $list ->current() . " " ;
$list ->next();
} ?> |
Output:
Welcome to GeeksforGeeks A Computer Science Portal
Reference: https://www.php.net/manual/en/spldoublylinkedlist.valid.php