How to change elements of a SplDoublyLinkedList<?php function change_elements($list,$old_index,$new_index){ $tmp1=$list->offsetGet($old_index);$tmp2=$list->offsetGet($new_index);$list->offsetSet($old_index,$tmp2);$list->offsetSet($new_index,$tmp1);}$list=new SplDoublyLinkedList(); $list->push("A");$list->push("B");$list->push("C");/*OUTPUTABC*/change_elements($list,0,1);/*OUTPUTBAC*/?>