http://www.perlmonks.org?node_id=19621


in reply to Acolyte needs regex help

Just a non-RE note. The -w is telling you, actually warning you, that you haven't declared the variables before using them. It is just a warning and doesn't prevent the script from running.

Update:
As Adam pointed out the -w is always good to use. So is use strict. I should have added that since you don't declare the variables before using them, their values will be set to null. Since the RE doesn't assign any values to the variables, they get the null value assigned to them.