How to convert SOAP response to PHP Array?

I am unable to convert SOAP response to Array in php.

here is the code

 $response = $client->__doRequest($xmlRequest,$location,$action,1);

here is the SOAP response.

<soap:envelope xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
<soap:body>
<searchflightavailability33response xmlns="http://FpwebBox.Fareportal.com/Gateway.asmx">
<searchflightavailability33result>
    &lt;Fareportal&gt;&lt;FpSearch_AirLowFaresRS&gt;&lt;CntKey&gt;1777f5a7-7824-46ce-a0f8-33d5e6e96816&lt;/CntKey&gt;&lt;Currency CurrencyCode="USD"/&gt;&lt;OriginDestinationOptions&gt;&lt;OutBoundOptions&gt;&lt;OutBoundOption segmentid="9W7008V21Feb14"&gt;&lt;FlightSegment etc....
    </searchflightavailability33result>
</searchflightavailability33response>
</soap:body>
</soap:envelope>;

i used the following ways to convert to Array,but i am getting empty output.

1.echo '<pre>';print_r($client__getLastResponse());
2.echo '<pre>';print_r($response->envelope->body->searchflightavailability33response);
3.echo '<pre>';print_r($client->SearchFlightAvailability33($response));
     4.simplexml_load_string($response,NULL,NULL,"http://schemas.xmlsoap.org/soap/envelope/");  

5.echo '<pre>';print_r($client->SearchFlightAvailability33($response));

please advice me.

finally i found the solution is

we can get body of the response from SOAP the following ways

example1:

$xml = new SimpleXMLElement($soapResponse);
foreach($xml->xpath('//soap:body') as $header) {
    $output = $header->registerXPathNamespace('default', 'http://FpwebBox.Fareportal.com/Gateway.asmx');    
}

example2:

$doc = new DOMDocument('1.0', 'utf-8');
    $doc->loadXML( $soapResponse );
    $XMLresults     = $doc->getElementsByTagName("SearchFlightAvailability33Response");
    $output = $XMLresults->item(0)->nodeValue;