Simple way to get the URI of the default namespace:
<?php
$document = new DOMDocument();
$document->load($xml_file);
$uri = $document->documentElement->lookupnamespaceURI(NULL);
?>
(PHP 5, PHP 7)
DOMNode::lookupNamespaceUri — Gets the namespace URI of the node based on the prefix
$prefix
) : string
Gets the namespace URI of the node based on the
prefix.
prefixThe prefix of the namespace.
The namespace URI of the node.
Simple way to get the URI of the default namespace:
<?php
$document = new DOMDocument();
$document->load($xml_file);
$uri = $document->documentElement->lookupnamespaceURI(NULL);
?>