How to delete the content of xml document through php_PHP tutorial

//1. Create a DOMDocument object. This object represents the xml file
$xmldoc = new DOMDocument();
//2. Load the xml file (specify which xml file to parse, then the dom tree node will be loaded into the memory)
$xmldoc->load("class.xml");
//3. Delete a student information record
//(1) Take out the root node
$root=$xmldoc->getElementsByTagName("class")->item(0);//When not deleting by node, this code is not needed
//(2)Find the student
$stu = $xmldoc->getElementsByTagName("student");
$stu_del = $stu->item(2);//Find the third student
$root->removeChild($stu_del);//Perform deletion operation, this is method 1
//$stu_del->parentNode->removeChild($stu_del);//Find its parent node, and the parent node performs the deletion operation. This is method 2
//4. Update xml document
$xmldoc->save("class.xml");
echo "Delete successfully";
?>

Second case: Delete one of the nodes under the student node, such as age:

The code is as follows: