PHP | DOMNode lookupPrefix() Function Last Updated : 28 Apr, 2025 Comments Improve Suggest changes Like Article Like Report The DOMNode::lookupPrefix() function is an inbuilt function in PHP which is used to get the namespace prefix of the node based on the namespace URI.Syntax: string DOMNode::lookupPrefix( string $namespaceURI ) Parameters: This function accepts a single parameter $namespaceURI which holds the namespace URI.Return Value: This function returns the prefix of the namespace.Below examples illustrate the DOMNode::lookupPrefix() function in PHP:Example 1: php <?php // Create a new DOMDocument instance $document = new DOMDocument(); // Load the XML with no namespace $document->loadXML("<?xml version=\"1.0\"?> <div > <h1> GeeksforGeeks </h1> </div> "); // Get the prefix with namespace URI "my_namespace" $prefix = $document->documentElement-> lookupPrefix("my_nsamespace"); echo $prefix; ?> Output: // Empty string as there is no such namespace Example 2: php <?php // Create a new DOMDocument instance $document = new DOMDocument(); // Load the XML with a namespace with prefix x $document->loadXML("<?xml version=\"1.0\"?> <div xmlns:x=\"my_namespace\"> <x:h1 x:style=\"color:red;\"> GeeksforGeeks </x:h1> </div> "); // Get the prefix with namespace URI "my_namespace" $prefix = $document->documentElement-> lookupPrefix('my_namespace'); echo $prefix; ?> Output: x Reference: https://www.php.net/manual/en/domnode.lookupprefix.php Comment More infoAdvertise with us Next Article PHP | DOMNode lookupPrefix() Function gurrrung Follow Improve Article Tags : Web Technologies PHP PHP-function PHP-DOM Similar Reads PHP | DOMNode lookupNamespaceUri() Function The DOMNode::lookupNamespaceUri() function is an inbuilt function in PHP which is used to get the namespace URI of the node based on the prefix. 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