Regular Expression to match valid dates

Question

I\'m trying to write a regular expression that validates a date. The regex needs to match the following

• M/D/YYYY
• MM/DD/YYYY
• Single digit mon

Answer 1

if you didn't get those above suggestions working, I use this, as it gets any date I ran this expression through 50 links, and it got all the dates on each page.

^20\d\d-(Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec)-(0[1-9]|[1-2][0-9]|3[01])$ 

Answer 2

This regex validates dates between 01-01-2000 and 12-31-2099 with matching separators.

^(0[1-9]|1[012])([- /.])(0[1-9]|[12][0-9]|3[01])\2(19|20)\d\d$

Answer 3

If you're going to insist on doing this with a regular expression, I'd recommend something like:

( (0?1|0?3| <...> |10|11|12) / (0?1| <...> |30|31) |
  0?2 / (0?1| <...> |28|29) ) 
/ (19|20)[0-9]{2}

This might make it possible to read and understand.