- simplexml_load_string: documentation ( source)
<?php
$xml = "<root>
<parent>
<child name='Child1'>AAAA</child>
<child name='Child2'>BBBB</child>
<subparent>
<child name='Child3'>CCCC</child>
</subparent>
</parent>
<child name='Child4'>DDDD</child>
</root>";
$xml = simplexml_load_string( $xml);
foreach( $xml->xpath( './/child[position() = 2]') as $child) {
echo $child->value(). "\n";
}