students.xml
<pre name="code" class="html"><?xml version="1.0" encoding="utf-8"?>
<students>
<student>
<name>小明</name>
<age>20</age>
<introduce>来自广东</introduce>
</student>
<student>
<name>小花</name>
<age>21</age>
<introduce>来自北京</introduce>
</student>
</students>
stu_update_dom.php
<?php
$xmldoc = new DOMDocument(); //1.创建DOMDocument对象
$xmldoc->load("students.xml"); //2.加载xml文件
//更新一个学生信息
$root = $xmldoc->getElementsByTagName("students")->item(0); //取出根节点
//找到所有student
$stus = $xmldoc->getElementsByTagName("student");
$stu = $stus->item(1); //确定要更新的student编号
$stu_age = $xmldoc->getElementsByTagName("age")->item(0); //定位好更新的Tag
$stu_age->nodeValue+=10; //更新age数据
//如果save是源文件名,则会对文件做更新处理
//如果save是新文件名,则会按文件名创建文件并保存
$xmldoc->save("students.xml");
?>
<?xml version="1.0" encoding="utf-8"?>
<students>
<student>
<name>小明</name>
<age>30</age>
<introduce>来自广东</introduce>
</student>
<student>
<name>小花</name>
<age>21</age>
<introduce>来自北京</introduce>
</student>
</students>