ruby - Regex to match Date

Question

I want to match dates with format mm/dd/yy or mm/dd/yyyy but it should not pick 23/09/2010 where month is 23 which is invalid nor some invalid date like 00/12/2020 or 12/00/2011.

Answer 1

Better than a crazy huge Regex (assuming this is for validation and not scanning):

require 'date'
def valid_date?( str, format="%m/%d/%Y" )
  Date.strptime(str,format) rescue false
end

And as an editorial aside: Eww! Why would you use such a horribly broken date format? Go for ISO8601, YYYY-MM-DD, which is a valid international standard, has a consistent ordering of parts, and sorts lexicographically as well.