$re = '@<div[^>]*gallery-image-border">[^>]*content="(?<url>[^"]*)"@mis';
$str = '<div id="gallery-image-border"> <meta itemprop="image" content="http://img.rnudah.com/images/04/044707022491864.jpg"> <span class="trackable favourite-heart favourite-heart-empty" aria-hidden="true" data-list-id="52002304" data-company-ad="0" data-category="4160" data-region="7" data-event_type="view" data-event_name="save_favourite_ad" data-page_name="Add Favourite Ad" data-xtn2="5" data-xiti_f1="4160" data-xiti_f2="7" data-xiti_f3="2" data-xiti_f4="2" data-xiti_f5="248"></span> <div class="heart-icon-tip adview-tip"> <div class="arrow-tip"></div> <div class="tip-content"> Click on the heart to add this to your Favourite list. </div> </div> <div id="gallery-image-container"><span><a href="javascript:void(0)" onclick="gallery.nextImage()"><img src="http://img.rnudah.com/images/04/044707022491864.jpg" style="margin-top:44px;margin-left:0px"></a></span></div> </div>';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php