SimpleXMLElement - Trying to get property of non-object

Question

In a response we receive an xml file, then convert to SimpleXMLElement, then access the elements and attributes as needed. However, we are getting "Trying to get property of non-object" when xml is loaded directly from string response vs from saved response.

//This code works
$response = simplexml_load_file( "response.xml" );
var_dump($response);
echo $response->RESPONSE->RESPONSE_DATA->FILE_INFORMATION['Order_Number'];

//Returns
//object(SimpleXMLElement)#153 (4) { ["@attributes"]=> array(1)...the rest of the xml file...
//Order_Number

//This code returns error
$response = simplexml_load_string( $response );
var_dump($response);
echo $response->RESPONSE->RESPONSE_DATA->FILE_INFORMATION['Order_Number'];

//Returns
//object(SimpleXMLElement)#153 (1) { [0]=> string(33864) "" }
//Notice: Trying to get property of non-object in...

What would cause the xml to fail when using simplexml_load_string instead of simplexml_load_file?

Here is a snippet of the xml file:

<?xml version="1.0" encoding="UTF-8"?>
<RESPONSE_GROUP>
    <RESPONSE>
        <RESPONSE_DATA>
            <FILE_INFORMATION Order_Number="19222835">
                ...
            </FILE_INFORMATION>
        </RESPONSE_DATA>
    </RESPONSE>
</RESPONSE_GROUP>

Answer 1

This works for me:

<?php

$response = '<?xml version="1.0" encoding="UTF-8"?>
<RESPONSE_GROUP>
    <RESPONSE>
        <RESPONSE_DATA>
            <FILE_INFORMATION Order_Number="19222835">
                ...
            </FILE_INFORMATION>
        </RESPONSE_DATA>
    </RESPONSE>
</RESPONSE_GROUP>';


//This code returns error
$response = simplexml_load_string( $response );
var_dump($response);
echo $response->RESPONSE->RESPONSE_DATA->FILE_INFORMATION['Order_Number'];


?>

Output:

object(SimpleXMLElement)#1 (1) {
  ["RESPONSE"]=>
  object(SimpleXMLElement)#2 (1) {
    ["RESPONSE_DATA"]=>
    object(SimpleXMLElement)#3 (1) {
      ["FILE_INFORMATION"]=>
      string(33) "
                ...
            "
    }
  }
}
19222835