Regex to identify whether a URL is an image or not?

Question

I am getting URLs like this:

http://img23.example.com/images/j43j32k3.jpg

And I need to identify whether it both:

a) Begins with HTTP

b) Ends with JPEG, JPG, GIF or PNG

I am using Ruby to do the matching I just don't know the Regex for this one..

Answer 1

The following regex delimited by /'s matches a string beginning with htpp and ending with one of the image extensions specified in your question

/\Ahttp.*(jpeg|jpg|gif|png)\Z/

Answer 2

%r{^http://.*\.(jpeg|jpg|gif|png)$}i