SplQueue::setIteratorMode Sets the mode of iteration &reftitle.description; voidSplQueue::setIteratorMode intmode &reftitle.parameters; mode There is only one iteration parameter you can modify. The behavior of the iterator (either one or the other): SplDoublyLinkedList::IT_MODE_DELETE (Elements are deleted by the iterator) SplDoublyLinkedList::IT_MODE_KEEP (Elements are traversed by the iterator) The default mode is: SplDoublyLinkedList::IT_MODE_FIFO | SplDoublyLinkedList::IT_MODE_KEEP The direction of iteration can not be changed for SplQueues, it is always SplDoublyLinkedList::IT_MODE_FIFO. &reftitle.returnvalues; &return.void; &reftitle.errors; Throws a RuntimeException on trying to change the direction of iteration by using SplDoublyLinkedList::IT_MODE_LIFO.