PHP | SplDoublyLinkedList setIteratorMode() Function

Last Updated : 21 Nov, 2019

The SplDoublyLinkedList::setIteratorMode() function is an inbuilt function in PHP which is used to set the mode of iteration.

Syntax:

void SplDoublyLinkedList::setIteratorMode( int $mode )

Parameters: This function accepts single parameter $mode which holds two orthogonal sets of modes which are listed below:
The direction of the iteration are:

SplDoublyLinkedList::IT_MODE_LIFO (Stack style)
SplDoublyLinkedList::IT_MODE_FIFO (Queue style)

The behavior of the iterator are:

SplDoublyLinkedList::IT_MODE_DELETE (Elements are deleted by the iterator)
SplDoublyLinkedList::IT_MODE_KEEP (Elements are traversed by the iterator)

Return Value: This function does not return any value.

Below programs illustrate the SplDoublyLinkedList::setIteratorMode() function in PHP:
Program 1:

<?php 
   
// Declare an empty SplDoublyLinkedList  
$list = new SplDoublyLinkedList(); 
   
// Add the element into SplDoublyLinkedList 
$list->setIteratorMode(SplDoublyLinkedList::IT_MODE_FIFO);  
   
// Use getIteratorMode() function 
$mode = $list->getIteratorMode(); 
var_dump($mode); 
   
// Add the element into SplDoublyLinkedList 
$list->setIteratorMode(SplDoublyLinkedList::IT_MODE_DELETE);  
   
// Use getIteratorMode() function 
$mode = $list->getIteratorMode(); 
var_dump($mode); 
   
// Add the element into SplDoublyLinkedList 
$list->setIteratorMode(SplDoublyLinkedList::IT_MODE_LIFO);  
   
// Use getIteratorMode() function 
$mode = $list->getIteratorMode(); 
var_dump($mode); 
   
?> 

Output:

int(0)
int(1)
int(2)

Program 2:

<?php 
   
// Declare an empty SplDoublyLinkedList  
$list = new SplDoublyLinkedList(); 
   
// Add the element into SplDoublyLinkedList 
$list->setIteratorMode(SplDoublyLinkedList::IT_MODE_FIFO 
                    | SplDoublyLinkedList::IT_MODE_DELETE 
                    | SplDoublyLinkedList::IT_MODE_LIFO);  
   
$mode = $list->getIteratorMode(); 
   
var_dump($mode & SplDoublyLinkedList::IT_MODE_FIFO); 
                   
var_dump($mode & SplDoublyLinkedList::IT_MODE_LIFO); 
                   
var_dump($mode & SplDoublyLinkedList::IT_MODE_DELETE); 
                   
var_dump($mode & SplDoublyLinkedList::IT_MODE_KEEP);  
   
?> 