Be careful SplStack mode is LIFO (Last In First Out) not FIFO (First in First Out) <?php// Array (FIFO)$stack = array();array_push($stack,"orange");array_push($stack,"banana");array_push($stack,"apple");array_push($stack,"raspberry");var_dump($stack);?>// resultarray (size=4) 0 => string 'orange' (length=6) 1 => string 'banana' (length=6) 2 => string 'apple' (length=5) 3 => string 'raspberry' (length=9)<?php// SplStack (LIFO)$stack = new SplStack();$stack ->push('orange');$stack ->push('banana');$stack ->push('apple');$stack->push('raspberry');$stack->rewind();while($stack->valid()){ var_dump($stack->current()); $stack->next(); }?>//result string 'raspberry' (length=9)string 'apple' (length=5)string 'banana' (length=6)string 'orange' (length=6)