regular expression advice

[dpm]

I have the contents of an HTML file as a variable $contents
I want to get a list of all image files used in the document.

I'm thinking that making a regular expression to extract the src information from each <img tag is a good start but I'm not sure:
a) how to write the expression
b) which function to use to return the results to an array

so I'm a bit stumped! Any advice gratefully received.

[[deleted]]

<?php
preg_match_all("/<img src=\"?(.+)\"? [^>]*>/Usi", $contents, $imgs);

print_r($imgs);
?>

consider the quotes !