<?php
//SplStack Mode is LIFO (Last In First Out)
 
$q = new SplStack();
$q[] = 1;
$q[] = 2;
$q[] = 3;
$q->push(4);
$q->add(4,5);
$q->rewind();
while($q->valid()){
 echo $q->current(),"\n";
 $q->next();
}
?>

Output
5
4
3
2
1