In PHP how can I read subvalue of an XML line?

Question

I have an XML line from a XML file:

<issue>
  <host ip="10.10.5.6">http://www.testing.com</host>

It is clear that I can read the host (http://www.testing.com) like this:

$simple = file_get_contents('/directory/test1.xml');
$test = new SimpleXMLElement($simple);
echo $test ->issue[1]->host;

But how can I read host ip (10.10.5.6) ?

Thank you for the help!

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Solution: echo $test ->issue[1]->host[ip];