How to get the file extension from a url?

Question

New to ruby, how would I get the file extension from a url like:

http://www.example.com/asdf123.gif

Also, how would I format this string, in c#

Answer 1

I realize this is an ancient question, but here's another vote for using Addressable. You can use the .extname method, which works as desired even with a query string:

 Addressable::URI.parse('http://www.example.com/asdf123.gif').extname # => ".gif"
 Addressable::URI.parse('http://www.example.com/asdf123.gif?foo').extname # => ".gif"