PHP | SplDoublyLinkedList valid() Function Last Updated : 21 Nov, 2019 Comments Improve Suggest changes Like Article Like Report 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 <?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 <?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 Comment More infoAdvertise with us Next Article PHP | SplDoublyLinkedList valid() Function jit_t Follow Improve Article Tags : Web Technologies PHP PHP-function PHP- SplDoublyLinkedList Similar Reads PHP SplDoublyLinkedList top() Function The SplDoublyLinkedList::top() function is an inbuilt function in PHP which is used to return the value of last (top) node in a doubly-linked list. Syntax: mixed SplDoublyLinkedList::top( void ) Parameters: This function does not accepts any parameters. Return Value: It returns the value of last nod 1 min read PHP | SplDoublyLinkedList unserialize() Function The SplDoublyLinkedList::unserialize() function is an inbuilt function in PHP which is used to unserialize the storage of SplDoublyLinkedList::serialize() function. Syntax: void SplDoublyLinkedList::unserialize( string $serialized ) Parameters: This function accepts single parameter $serialized whic 2 min read PHP SplDoublyLinkedList unshift() Function 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 2 min read PHP SplDoublyLinkedList pop() Function The SplDoublyLinkedList::pop() function is an inbuilt function in PHP which is used to pop the node from the end of the doubly linked list. Syntax: mixed SplDoublyLinkedList::pop( void ) Parameters: This function does not accept any parameters. Return Value: This function returns the value of a popp 1 min read PHP SplDoublyLinkedList key() Function 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 il 1 min read PHP SplDoublyLinkedList prev() Function The SplDoublyLinkedList::prev() function is an inbuilt function in PHP which is used to move to the previous entry. Syntax: void SplDoublyLinkedList::prev( void ) Parameters: This function does not accepts any parameters. Return Value: It does not return any value. Below programs illustrate the SplD 1 min read PHP SplDoublyLinkedList push() Function The SplDoublyLinkedList::push() function is an inbuilt function in PHP which is used to push an element at the end of the doubly linked list. Syntax: void SplDoublyLinkedList::push( $value ) Parameters: This function accepts a single parameter $value which holds an element to push it at the end of d 1 min read PHP SplDoublyLinkedList next() Function The SplDoublyLinkedList::next() function is an inbuilt function in PHP which is used to move the index into next index. Syntax: void SplDoublyLinkedList::next( void ) Parameters: This function does not accept any parameter. Return Value: It does not return any value. Below programs illustrate the Sp 1 min read PHP SplDoublyLinkedList count() function The SplDoublyLinkedList::count() function is an inbuilt function in PHP which is used to count the number of elements present in a doubly linked list. Syntax: int SplDoublyLinkedList::count( void ) Parameters: It does not contain any parameter. Return Value: It returns the number of elements present 1 min read PHP SplDoublyLinkedList shift() Function The SplDoublyLinkedList::shift() function is an inbuilt function in PHP which is used to shift the node from the beginning of the doubly linked list. Syntax: mixed SplDoublyLinkedList::shift( void ) Parameters: This function does not accepts any parameters. Return Value: It returns the value of shif 1 min read Like