Find pattern in PHP string

Hi,

In order to facilitate multiple countries, each country will have a website URL as below:

http://www.somewhere.com/ie/index.html       (for Ireland)
http://www.somewhere.com/fr/index.html       (for France)

I'm trying to extract the 2 character country code between the forwardslashes (it will always be 2 characters long). I'm guessing I need a Regexp but I have no idea how to use them.

In English, the pattern would be /XX/ where XX is what needs to be stored in a PHP variable. The position of the string /XX/ would not be fixed as I need this working using http://localhost/folder as well as http://server/folder and http://www........

Can somebody please provide some direction on how I can get started?

Thanks in advance