Inserting child element and data by addChild function

xml-sample1.php

<?Php
require "xml-sample1.php";
$main1 = new SimpleXMLElement($str_xml);
$add=$main1->addChild('Job');
$add->addChild('designation','Manager');
echo $main1->asXML(); 
?>

<?Php
require "xml-sample1.php";
$main1 = new SimpleXMLElement($str_xml);
$add=$main1->addChild('Job');
$add->addChild('designation','Manager');

$add=$main1->address->addChild('parent_name');
$add->addChild('father','Rony Jack');
$add->addChild('mother','Liena');

echo $main1->asXML(); 
?>

<?xml version="1.0" standalone="true"?>
-<details> 
<name>Abcd</name> 
-<address> 
<door_no>234-ac</door_no> 
<street>Great Wall</street> 
<city>Alabama</city> 
	-<parent_name>
		<father>Rony Jack</father>
		<mother>Liena</mother>
	</parent_name>
</address> 
-<Job>
<designation>Manager</designation></Job>
</details>

Example using xml-sample2.xml

header('Content-Type: text/xml');

$str_xml = simplexml_load_file("xml-sample2.xml");
$main1 = new SimpleXMLElement($str_xml->asXML());
$add=$main1->addChild('Job');
$add->addChild('designation','Manager');

$add=$main1->address->addChild('parent_name');
$add->addChild('father','Rony Jack');
$add->addChild('mother','Liena');

$add=$main1->addChild('class','Four');
$add=$main1->addChild('Mark',70);

echo $main1->asXML();

<details>
<name>Abcd</name>
<address>
<door_no>234-ac</door_no>
<street>Great Wall</street>
<city>Alabama</city>
<parent_name>
<father>Rony Jack</father>
<mother>Liena</mother>
</parent_name>
</address>
<Job>
<designation>Manager</designation>
</Job>
<class>Four</class>
<Mark>70</Mark>
</details>