<?php

 header("Content-type:text/html; charset=utf-8");

 $stack = new SplStack();

 //LIFO

 echo 'stack push',PHP_EOL;

 //入栈

 $stack->push('hello');

 $stack->push('world');

 $stack->push('web');

 $stack[] = 'site';

 $stack[] = 'devlop';

 echo '***************',PHP_EOL;

 //设置index为 0 的元素（栈顶）的值为 DEVLOP，遍历栈

 $stack->offsetSet(0, 'DEVLOP');

 foreach($stack as $val) {

     echo $val,PHP_EOL;

 }

 echo '***************',PHP_EOL;

 //查看栈元素个数

 echo '栈内有',$stack->count(),'个元素',PHP_EOL;

 echo '栈内有',count($stack),'个元素',PHP_EOL;

 echo '***************',PHP_EOL;

 //查看栈顶、栈底元素

 echo '栈顶元素是',$stack->top(),PHP_EOL;

 echo '栈底元素是',$stack->bottom(),PHP_EOL;

 echo '***************',PHP_EOL;

 //遍历栈

 foreach($stack as $val) {

     echo $val,PHP_EOL;

 }

 echo '***************',PHP_EOL;

 //出栈

 while($stack->count() != 0) {

     echo '栈顶元素是:',$stack->top(),PHP_EOL;

     $stack->pop();

 }

stack push

***************

DEVLOP

site

web

world

hello

***************

栈内有5个元素

栈内有5个元素

***************

栈顶元素是DEVLOP

栈底元素是hello

***************

DEVLOP

site

web

world

hello

***************

栈顶元素是:DEVLOP

栈顶元素是:site

栈顶元素是:web

栈顶元素是:world

栈顶元素是:hello