php 读xml的两种方式

<?xml version="1.0" encoding="ISO-8859-1"?>
<st>
<stu>
<name>sunzhiyan</name>
<sex>men</sex>
<age>20</age>
</stu><stu>
<name>sunxin</name>
<sex>women</sex>
<age>18</age>
</stu>
<stu>
<name>wanghuilin</name>
<sex>men</sex>
<age>20</age>
</stu>
</st>

<?php $xml = new DoMDocument();$xml->load("xml.xml");
$root = $xml->getElementsByTagName("st")->item(0);$stu = $xml->createElement("stu");
//name
$stu_name = $xml->createElement("name");
$stu_name->nodeValue = "wanghuilin";
//sex
$stu_sex = $xml->createElement("sex");
$stu_sex->nodeValue = "men";
//age
$stu_age = $xml->createElement("age");
$stu_age->nodeValue = "20";
$stu->appendChild($stu_name);
$stu->appendChild($stu_sex);
$stu->appendChild($stu_age);
$root->appendChild($stu);$xml->save("xml.xml");?>

<?
$xml = simplexml_load_file('xml.xml');$name = $xml->stu;
echo $name[0]->name;?>