如何检查simpleXML是否为null

Question

So, I build a script which contains multi curl to verify the XML and extrac $xml->loc from more urls but my script crash(stop) when he found anything else which is not a xml file

...multi curl code...
    if($httpcode>=200 && $httpcode<=300) {
        $xml = new SimpleXMLElement($data);
        if($xml !== NULL) {
            foreach ($xml->url as $url_list) {
            $url = $url_list->loc;
            $newurls[] = $url;
            }
        }
    }

If i put 5 valid xml urls it works but if I put 100 link and one of them is not a XML file the script stops.

ERROR:

[root@test ~]# php a z2
PHP Fatal error:  Uncaught exception 'Exception' with message 'String could not be parsed as XML' in /root/a:160
Stack trace:
#0 /root/a(160): SimpleXMLElement->__construct('
<!DOCTYPE htm...')
#1 /root/a(65): mycurl_done('http://southpas...', '
<!DOCTYPE htm...', Resource id #36)
#2 /root/a(175): ThreadsLoop()
#3 {main}
  thrown in /root/a on line 160
[root@test ~]#

Seems like my script try to extract information from a html file because if the file don't exist it will redirect me to homepage(I guess)... What options do I have to make to continue if the SimpleHTMLElement can't parse my $data variable which is the entire source code from a XML file?

Answer 1

You can use a try catch block to handle the exception.

try {
  $xml = new SimpleXMLElement($data);
  //XML is valid
  ...
} catch(Exception $e) {
  //XML is invalid
}