php线性标的入栈与出栈

<?php$stack = array("Simon", "Elaine");//定义数组array_push($stack, "Helen", "Peter");//入栈print_r($stack);?> 

<?php$stack = array("Simon", "Elaine");//定义数组array_unshift ($stack, "Helen", "Peter");//入栈print_r($stack);?>  

<?php$stack = array("Simon", "Elaine", "Helen", "Peter");echo array_pop($stack).”/n”;//出栈print_r($stack);?>

<?php$stack = array("Simon", "Elaine", "Helen", "Peter");echo array_shift($stack)."/n";//出栈print_r($stack);?>