Checking if xml is valid

gistfile1.php

// The function checks if xml is valid
function is_valid_xml ( $xml ) {

    if( empty( $xml ) ){

        return null;

    }    

    libxml_clear_errors();

    libxml_use_internal_errors( true );

    $doc = new DOMDocument('1.0', 'utf-8');

    $doc->loadXML( $xml );

    $errors = libxml_get_errors();

    return empty( $errors );

}