Worst regular expression ever

A couple of days ago, I had to do some simple date and time validation using regex. The format to validate was yyyy-mm-dd hh:mm. It looks simple enough and like always, I thought I could find the regex on the web, but I couldn’t.

I was under a tight deadline and the date/time validation was not that important, so I made a decision to make the worst regex the world have ever seen. Maybe it’s long, ugly and wrong, but it works just enough to make me use it until I have the time to make a better one.

Warning, do not try this at home!

[0-9][0-9][0-9][0-9]-[0-9][0-9]-[0-9][0-9] [0-9][0-9]:[0-9][0-9]

The good thing about regex is that they are always ugly, most of them are long and only five people in the world understand them enough to see if they work or not.