I'm trying to match the file extension of an html link, and matching the one PREVIOUS to the last one when there are two of them, to get the original file extension, not the extension added by the archive. So for "file.ai.zip" $2 should match "ai". Here's the one I came up with, but $2 and $3 ALWAYS match ...

Hi, Anybody out there, I'd be immensly greatful if you helped me fix one regular expressions of mine. Basically I've written a regular expression in PHP identifying a pattern of a certain type of URL REGEX: /(http\:\/\/dx\.doi\.org\/.*?)(\s|$|;|>)/ it will catch strings of URLs from the 'http://dx.doi.org/' domain, looking ...