Addchild() and addattribute() functions in PHP

> addChild

<?php   
        /*SimpleXMLElement::addChild() Function acceptance representation XML The string value of the key and value of the element 
                 And add it as a child element to XML node */

        $str = "<?xml version='1.0' encoding='UTF-8'?><Tutorial><Name>aa</Name></Tutorial>";
        $xml = new SimpleXMLElement($str);
        $tut = $xml->addChild('Tu');
        $tut->addChild('Price', '60');
        $simpleXml = $xml->asXML();
        print_r($simpleXml);
/*
<?xml version="1.0" encoding="UTF-8"?>
<Tutorial>
	<Name>aa</Name>
	<Tu>
		<Price>60</Price>
	</Tu>
</Tutorial>
*/
?>

> addAttribute

<?php
    $str = "<?xml version='1.0' encoding='UTF-8'?><Tutorial><Name>aa</Name></Tutorial>";
    $xml = new SimpleXMLElement($str);

    $xml->addAttribute("type", "private");
    $xml->Name->addAttribute("date", "2022");
    echo $xml->asXML();
    
    /** grammar addAttribute(name, value, ns)
     * name  It's necessary .  Specify the name of the attribute to be added 
     * value  Optional . Specify the value of the property 
     * ns  Optional .  Specify the namespace of the attribute 
     */
    /*
    <?xml version="1.0" encoding="UTF-8"?>
    <Tutorial type="private"><Name date="2022">aa</Name></Tutorial>
    */
?>