How to: Extract file extension with PHP

People from other scripting languages always think theirs is better because they have a built in function to do that and not PHP (I am looking at pythonistas right now.

In fact, it does exist, but few people know it. Meet pathinfo():

$ext = pathinfo($filename, PATHINFO_EXTENSION);

This is fast, efficient, reliable and built-in. pathinfo() can give you other information, such as canonical path, depending on the constant you pass to it.