students.xml

<?xml version="1.0" encoding="utf-8"?>
<students>
	<student>
		<name>小明</name>
		<age>10</age>
		<introduce>来自广东</introduce>
	</student>
	<student>
		<name>小花</name>
		<age>21</age>
		<introduce>来自北京</introduce>
	</student>

<student sex="female"><name>小白</name><age>20</age><introduce>来自上海</introduce></student></students>

<?PHP

$xmldoc = new DOMDocument();	//1.创建DOMDocument对象
$xmldoc->load("students.xml");	//2.加载xml文件

//删除一个学生信息
$root = $xmldoc->getElementsByTagName("students")->item(0);    //取出根节点

//找到所有student
$stus = $xmldoc->getElementsByTagName("student");
$stu = $stus->item(2);	//确定要删除的student编号

//$root->removeChild($stu);				//第一种删除方法
$stu->parentNode->removeChild($stu);	//第二种删除方法

//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>10</age>
		<introduce>来自广东</introduce>
	</student>
	<student>
		<name>小花</name>
		<age>21</age>
		<introduce>来自北京</introduce>
	</student>

</students>