Correct Regular expressions to match a date

Question

What is the correct regular expression to use to validate a date like. 2009-10-22 or 2009-01-01 etc. Platform PHP

Answer 1

found this on the web tested it with a few dates and looks stable, for dates between 1900 and 2000:

(19|20)\d\d[- /.](0[1-9]|1[012])[- /.](0[1-9]|[12][0-9]|3[01])