The SplDoublyLinkedList class

FIFO and LIFO in SplDoublyLinkedList$list = new SplDoublyLinkedList();$list->push('a');$list->push('b');$list->push('c');$list->push('d'); echo "FIFO (First In First Out) :\n";$list->setIteratorMode(SplDoublyLinkedList::IT_MODE_FIFO);for ($list->rewind(); $list->valid(); $list->next()) {    echo $list->current()."\n";} Result :// FIFO (First In First Out):// a// b// c// d echo "LIFO (Last In First Out) :\n";$list->setIteratorMode(SplDoublyLinkedList::IT_MODE_LIFO);for ($list->rewind(); $list->valid(); $list->next()) {    echo $list->current()."\n";} Result :// LIFO (Last In First Out):// d// c// b// a

/*php doubly link list is an amazing data structure ,doubly means you can traverse forward as well as backward, it can act as a deque(double ended queue) if you want it to,here is how it works *///instantiating an object of doubly link list$dlist=new SplDoublyLinkedList();//a push inserts data at the end of the list $dlist->push('hiramariam');$dlist->push('maaz');$dlist->push('zafar');/* the list containshiramariammaazzafar*/ //while an unshift inserts an object at top of the list$dlist->unshift(1);$dlist->unshift(2);$dlist->unshift(3);/* the list now contains321hiramariammaazzafar*/ //you can delete an item from the bottom of the list by using pop$dlist->pop();/* the list now contains321hiramariammaaz*/ //you can delete an item from the top of the list by using shift()$dlist->shift();/* the list now contains21hiramariammaaz*/ /* if you want to replace an item at particular index you can use a method named add , note that if you want to replace an item that does not exist , an exception will be thrown*/$dlist->add(3 , 2.24);/*to go through the list we use a simple for loop, the rewind() method shown below point to the initials of the list depending on the iterator, a valid() method checks whether a list is still valid or not , meaning it ensures the loop does not go on and on after we reach the last data in the list , and the next() method simply points to the next data in the list.*/for($dlist->rewind();$dlist->valid();$dlist->next()){        echo $dlist->current()."<br/>";    }echo "<br/>";/*To traverse backward */$dlist->setIteratorMode(SplDoublyLinkedList::IT_MODE_LIFO);for($dlist->rewind();$dlist->valid();$dlist->next()){        echo $dlist->current()."<br/>";;    }

<?php$splDoubleLinkedList = new SplDoublyLinkedList();$splDoubleLinkedList->push('a');$splDoubleLinkedList->push('3');$splDoubleLinkedList->push('v');$splDoubleLinkedList->push('1');$splDoubleLinkedList->push('p');//First of all, we need rewind list$splDoubleLinkedList->rewind();//Use while, check if the list has valid nodewhile ($splDoubleLinkedList->valid()){    //Print current node's value    echo $splDoubleLinkedList->current()."\n";    //Turn the cursor to next node    $splDoubleLinkedList->next();}?>

A function which replaces some portion od doubly linked list (DLL) with items from specified array.<?php/** * Replace some portion (specified by index and length) of DLL with items * from the specified replacement array. */public function dll_splice(    \SplDoublyLinkedList $dll,    int $start,    int $length,    array $replacement,): void {    if ($start < 0 || ($start + $length) > $dll->count()) {        throw new \OutOfRangeException("Invalid range for splicing");    }    for ($i = 0; $i < $length; $i++) {        $dll->offsetUnset($start);    }    foreach ($replacement as $item) {        $dll->add($start, $item);    }}?>

$list = new SplDoublyLinkedList();for ($i = 0; $i < 2000001; $i++) {    $list->push($i);}$s = microtime(true);//$res = $list->offsetGet(2000000);     // spend 7 ms$res = $list->offsetGet(0);               // spend 0.07 msvar_dump($res);$e = microtime(true);echo ($e - $s) * 1000;

$a = new SplDoublyLinkedList;$arr=[1,2,3,4,5,6,7,8,9];for($i=0;$i<count($arr);$i++){    $a->add($i,$arr[$i]);}$a->push(11); //push method$a->add(10,12); //add method must with index$a->shift(); //remove array first value$a->unshift(1); //add first value$a->rewind(); //initial from first echo "SplDoublyLinkedList array last/top value " .  $a->top() ." \n";echo "SplDoublyLinkedList array count value " .  $a->count() ." \n";echo "SplDoublyLinkedList array first/top value " . $a->bottom() . " \n\n";while($a->valid()){ //check with valid method    echo 'key ', $a->key(), ' value ', $a->current(),"\n"; //key and current method use here    $a->next(); //next method use here}$a->pop(); //remove array last valueprint_r($a);$s=$a->serialize();echo $s;//OutputSplDoublyLinkedList array last/top value 12 SplDoublyLinkedList array count value 11 SplDoublyLinkedList array first/top value 1 key 0 value 1key 1 value 2key 2 value 3key 3 value 4key 4 value 5key 5 value 6key 6 value 7key 7 value 8key 8 value 9key 9 value 11key 10 value 12SplDoublyLinkedList Object(    [flags:SplDoublyLinkedList:private] => 0    [dllist:SplDoublyLinkedList:private] => Array        (            [0] => 1            [1] => 2            [2] => 3            [3] => 4            [4] => 5            [5] => 6            [6] => 7            [7] => 8            [8] => 9            [9] => 11        ))i:0;:i:1;:i:2;:i:3;:i:4;:i:5;:i:6;:i:7;:i:8;:i:9;:i:11;