PHP中如何将XML文件处理结果存入变量？

$string = <<<XML<?xml version="1.0" encoding="utf-8" ?><returnsms>    <returnstatus>status</returnstatus>    <message>message</message>    <remainpoint>remainpoint</remainpoint>    <taskID>taskID</taskID>    <successCounts>successCounts</successCounts></returnsms>XML;$xmlResult = simplexml_load_string($string);foreach ($xmlResult->children() as $childItem) {    $xml_l[] = $childItem->getName() . ':' . $childItem;}print_r($xml_l);