Function php

Hi guys, having a little problem with a plugin (Flipbook) I’m getting this message on the pages that the flipbook appears:

Warning: preg_match() [function.preg-match]: No ending delimiter ‘^’ found on line 666 in file /websites/123reg/LinuxPackage22/yu/mm/ym/yummymummy-cakes.co.uk/public_html/wp-content/plugins/page-flip-image-gallery/functions.class.php

This is the code on that line 666:

return preg_match("^http:\/\/[-0-9a-z\._]+.*$/i", trim( $url ));

can anyone tell me if there is anything wrong with this, or what it should look like?

Thanks