How does Stack Overflow generate its SEO-friendly URLs?

Question

What is a good complete regular expression or some other process that would take the title:

How do you change a title to be part of the URL like Stack

Answer 1

Brian's code, in Ruby:

title.downcase.strip.gsub(/\ /, '-').gsub(/[^\w\-]/, '')

downcase turns the string to lowercase, strip removes leading and trailing whitespace, the first gsub call globally substitutes spaces with dashes, and the second removes everything that isn't a letter or a dash.