You would better not to use regular expressions where you can use proper tools. Something which comes to my mind (although maybe it can be done easier):

$descr = $rss[description]; // String. You have extracted description part from your feed

$dom = new DOMDocument();
$dom-&gt;loadHTML($descr); // or you can use loadXML
if (!$dom) {
    die('Error loading HTML string.');
}

$xml = simplexml_import_dom($dom);
$imgSrc = (string)$xml-&gt;body-&gt;div-&gt;a-&gt;img['src'];


Here we go. Based on the your example CDATA $imgSrc will be equal to img_url.

How to get <img> src from CDATA in RSS?
This question is related to Planck units (also called natural units, absolute units or God's units).
I'm wondering which constant is the most fundamental and should be normalized to 1. I would like as much explanation as possible please.
