Question

I am reading an XML feed and would like to compare to an old version to check for updates.

My problems at the moment are that I can’t seem to make a copy of a SimpleXML object, and the other problem is I’m not sure I can directly compare them.

This is my code as it stands. I’m obviously just testing on local files, but I intend to eventually load from the web.

Is it okay to use sleep for very long periods? I was thinking 15 minute interval is often enough for my purpose.

error_reporting(E_NOTICE);
$file = 'tmbdata_sm.xml';

$xml_old = "";
while(true){
 $xml = simplexml_load_file($file);

 if($xml != $xml_old){
    foreach($xml->channel->item as $item){
        echo $item->title . "\n";
        echo $item->link . "\n";
    }
    $xml_old = clone $xml;
    $xml = "";
 }else{
    echo 'no change';
 }

sleep(60);
}

Answer 1

I think you can’t compare simple xml objects in this way.

I would try to download the xml using whatever you feel comfortable with (say, cURL extension), then compare the xml text strings, and then when you find they are different, use simplexml_load_string() to parse the xml text.