SimpleXml to string

You can use the SimpleXMLElement::asXML() method to accomplish this:

$string = "<element><child>Hello World</child></element>";
$xml = new SimpleXMLElement($string);

// The entire XML tree as a string:
// "<element><child>Hello World</child></element>"
$xml->asXML();

// Just the child node as a string:
// "<child>Hello World</child>"
$xml->child->asXML();

You can use casting:

<?php

$string = "<element><child>Hello World</child></element>";
$xml = new SimpleXMLElement($string);

$text = (string)$xml->child;

$text will be 'Hello World'

You can use the asXML method as:

<?php

// string to SimpleXMLElement
$xml = new SimpleXMLElement($string);

// make any changes.
....

// convert the SimpleXMLElement back to string.
$newString = $xml->asXML();
?>