SplStack::setIteratorMode Sets the mode of iteration &reftitle.description; public voidSplStack::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 0x2 : SplDoublyLinkedList::IT_MODE_LIFO | SplDoublyLinkedList::IT_MODE_KEEP The direction of iteration can no longer be changed for SplStacks. Trying to do so will result in a RuntimeException being thrown. &reftitle.returnvalues; &return.void;