如何在php中将xml转换为数组？

My code is like this :

我的代码是这样的:

$xmlstring = '<Response>
                    <Auth>
                        <UserID>test</UserID>
                        <UserIP>123</UserIP>
                        <XmlVersion>Testing Version</XmlVersion>
                    </Auth>
                    <SearchAvailRequest>
                        <CountryCd>ID</CountryCd>
                        <CityCd>JOG</CityCd>
                        <CheckIn>2016-01-08</CheckIn>
                        <CheckOut>2016-01-09</CheckOut>
                    </SearchAvailRequest>
                    <SearchAvailResponse>
                        <Hotel>
                            <HotelNo>1</HotelNo>
                            <HotelCode>321</HotelCode>
                            <HotelName>Test 1 Hotel</HotelName>
                            <RmGrade>Deluxe</RmGrade>
                            <RmGradeCode>DLX</RmGradeCode>
                        </Hotel>
                        <Hotel>
                            <HotelNo>2</HotelNo>
                            <HotelCode>212</HotelCode>
                            <HotelName>Test 2 & 1 Hotel</HotelName>
                            <RmGrade>Deluxe</RmGrade>
                            <RmGradeCode>DLX</RmGradeCode>
                        </Hotel>
                    </SearchAvailResponse>
                </Response>';

    $xml = simplexml_load_string($xmlstring, "SimpleXMLElement", LIBXML_NOCDATA);
    $json = json_encode($xml);
    $array = json_decode($json,TRUE);
    echo '<pre>';print_r($array);echo '</pre>';
?>
$xmlstrin