XML转换成PHP数组方法

$xml_php = "<xml> 
   <appid>wx123ASb1c23370ec43b</appid> 
   <customs>ZHONGWEN_AA</customs> 
   <mch_customs_no>D54841</mch_customs_no> 
   <mch_id>1548254101</mch_id> 
   <order_fee>12310</order_fee> 
   <out_trade_no>12112394212604</out_trade_no> 
   <product_fee>13110</product_fee> 
   <sign>2FF6CEF879FB9123CD580222E671E9D4</sign> 
   <transaction_id>500623231201511241751403478</transaction_id> 
   <transport_fee>0</transport_fee> 
   <fee_type>CNY</fee_type> 
   <sub_order_no>13612496832676251</sub_order_no> 
</xml>";

转换函数：
function xmlToArray($str) { 
    // 将XML转为array 
    $array_data = json_decode(json_encode(simplexml_load_string($str, 'SimpleXMLElement', LIBXML_NOCDATA)), true); 
    return $array_data; 
}

转换后：
print_r(xmlToArray($str));