DateTime Regex Validator

Question

I want a regex which works for following criteria for a DateTime:

DateTime must be in MM/dd/yyyy hh:mm:ss AM/PM
If only date is entered in MM/dd/yyyy then also it is valid.
In date month and day must be in two digit.

I tried following regular expression but it don't work for some dates like: 12/12/2012

[RegularExpression(@"^((((((0?[13578])|(1[02]))[\-\/\s]?((0?[1-9])|([1-2][0-9])|(3[01])))|(((0?[469])|(11))[\-\/\s]?((0?[1-9])|([1-2][0-9])|(30)))|(0?2[\-\/\s]?((0?[1-9])|([1-2][0-9]))))[\-\/\s]?\d{2}(([02468][048])|([13579][26])))|(((((0?[13578])|(1[02]))[\-\/\s]?((0?[1-9])|([1-2][0-9])|(3[01])))|(((0?[469])|(11))[\-\/\s]?((0?[1-9])|([1-2][0-9])|(30)))|(0?2[\-\/\s]?((0?[1-9])|(1[0-9])|(2[0-8]))))[\-\/\s]?\d{2}(([02468][1235679])|([13579][01345789]))))(\s(((0?[1-9])|(1[0-2]))\:([0-5][0-9])((\s)|(\:([0-5][0-9])\s))([AM|PM|am|pm]{2,2})))?$", ErrorMessage = "Please enter valid date.")]

That's **the regex**... Why don't you validate the date via parsing? — Ulugbek Umirov, Jun 10 '14 at 07:29
As example: [DateTime (date and hour) validation with Data Annotation](http://stackoverflow.com/questions/5390403/datetime-date-and-hour-validation-with-data-annotation). Btw, your regex accepts `12/12/2012` without problem: http://regex101.com/r/mQ8qA4 — Ulugbek Umirov, Jun 10 '14 at 07:40
why don't you use `DateTime.TryParse`. That way you make sure your really accept only valid datetimes. — Wolfgang Ziegler, Jun 10 '14 at 08:34

Ulugbek Umirov · Accepted Answer · 2014-06-10T08:31:06.850

2

If you insist on regex solution, I modified yours a bit (to restrict it to rules you provided):

^(?:(?:(?:(?:(?:(?:0[13578])|(?:1[02]))\/(?:(?:0[1-9])|(?:[1-2][0-9])|(?:3[01])))|(?:(?:(?:0[469])|11)\/(?:(?:0[1-9])|(?:[1-2][0-9])|30))|(?:02\/(?:(?:0[1-9])|(?:[1-2][0-9]))))\/\d{2}(?:(?:[02468][048])|(?:[13579][26])))|(?:(?:(?:(?:(?:0[13578])|(?:1[02]))\/(?:(?:0[1-9])|(?:[1-2][0-9])|(?:3[01])))|(?:(?:(?:0[469])|(?:11))\/(?:(?:0[1-9])|(?:[1-2][0-9])|(?:30)))|(?:02\/(?:(?:0[1-9])|(?:1[0-9])|(?:2[0-8]))))\/\d{2}(?:(?:[02468][1235679])|(?:[13579][01345789]))))(?:\s(?:(?:(?:0[1-9])|(?:1[0-2]))\:(?:[0-5][0-9])(?:\:(?:[0-5][0-9])\s))(?:AM|PM|am|pm))?$

Demo

Slightly simplified regex (correctly validates dates in 0000-9999 range):

^(?:(?:(?:(?:(?:0[13578]|1[02])\/(?:0[1-9]|[1-2][0-9]|3[01]))|(?:(?:0[469]|11)\/(?:0[1-9]|[1-2][0-9]|30))|(?:02\/(?:0[1-9]|1[0-9]|2[0-8]))))\/\d{4}|02\/29\/(?:(?:\d{2}(?:04|08|[2468][048]|[13579][26]))|(?:(?:[02468][048])|[13579][26])00))(?:\s(?:0[1-9]|1[0-2])\:[0-5][0-9]\:[0-5][0-9]\s(?:AM|PM|am|pm))?$

Demo

edited Jun 10 '14 at 08:31

answered Jun 10 '14 at 07:54

Ulugbek Umirov

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whats difference between dark blue and light blue? – Dhwani Jun 10 '14 at 08:55
@Dhwani These are just alternate colors so you don't think that it is a single match. – Ulugbek Umirov Jun 10 '14 at 08:58
1

+1 for changing the color of the matrix, I was getting tired of black and green. :) – zx81 Jun 10 '14 at 09:51
@UlugbekUmirov okie. will d{2} take year length of 2 digit? – Dhwani Jun 10 '14 at 10:03
@Dhwani Please, clarify your comment. In your original regex and in regexes I posted `d{2}` is used only as century. – Ulugbek Umirov Jun 10 '14 at 10:16
@UlugbekUmirov I mean century of last 2 digit? or 4 dgit? – Dhwani Jun 10 '14 at 10:30
@Dhwani Century consists of first 2 digits. Full year is always 4 digits (even in case of `0000`). – Ulugbek Umirov Jun 10 '14 at 10:31
@UlugbekUmirov I want 4 digit full year. – Dhwani Jun 10 '14 at 10:32
@UlugbekUmirov last one regex? – Dhwani Jun 10 '14 at 10:34
@Dhwani Both of them. But last one is valid for all leap years. The first one (made by cleaning of yours) has problems with `1900`, `2100` years (not leap because divisible by 100 and not divisible by 400). – Ulugbek Umirov Jun 10 '14 at 10:37

DateTime Regex Validator

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