C# Regular Expression to validate a date?

Question

I am trying to validate a date entered into a text box. There is an input mask on the textbox which forces input of xx/xx/xxxx. I am trying to use a regular expression validator to enforce that a correct date is entered. I am not skilled in RegEx bascially at all. My co-worker found this one on the internet but I can't really tell what it's doing.

Does this look right? Seems overly complicated...

(^((((0[1-9])|([1-2][0-9])|(3[0-1]))|([1-9]))\x2F(((0[1-9])|(1[0-2]))|([1-9]))\x2F(([0-9]{2})|(((19)|([2]([0]{1})))([0-9]{2}))))$)

Does anyone know of a less complex expression that essentially does what I need?

This has been addressed in [this](http://stackoverflow.com/questions/669741/date-regex) post. See if it helps. — JYelton, Aug 31 '09 at 20:13

Donut · Answer 1 · 2009-08-31T20:30:41.990

35

Why not use one of the methods available in the System.DateTime namespace? You could use DateTime.TryParse() (edit: DateTime.TryParseExact() is probably the right suggestion) to accomplish the validation.

edited Aug 31 '09 at 20:30

answered Aug 31 '09 at 20:14

Donut

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And DateTime.TryParseExact() may be more appropriate depending on your exact needs. – Matthew Vines Aug 31 '09 at 20:17
What if I wanna make sure the the date is correct at the button click itself? – Muhammedh Nov 17 '13 at 08:11
+1 dont reinvent the wheel. Additionally, regex should not be use for validating the _parsed value_ of a string, only the _form_ of the string, to ensure that you can parse it. If it parses a proper pattern, you should not need `TryParse`. – Gusdor Nov 17 '13 at 08:17

score 25 · Answer 2 · edited Dec 23 '11 at 09:53

25

You can use DateTime.TryParseExact:

DateTime dt;

bool isValid = DateTime.TryParseExact(
    "08/30/2009",
    "MM/dd/yyyy",
    CultureInfo.InvariantCulture,
    DateTimeStyles.None,
    out dt);

edited Dec 23 '11 at 09:53

bluish

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answered Aug 31 '09 at 20:17

dtb

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score 7 · Answer 3 · edited Dec 13 '12 at 06:26

7

This would be correct regular expression to use for date format dd/mm/yyyy

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

edited Dec 13 '12 at 06:26

akjoshi

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answered Dec 13 '12 at 06:09

Radha

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Not exactly - you need to make the initial zero optional or it won't match single digit day values like 2/12/2012. ^(0?[1-9]|[12][0-9]|3[01])[- /.](0[1-9]|1[012])[- /.](19|20)\d\d$ – immutabl May 17 '13 at 10:04

score 3 · Answer 4 · edited Nov 15 '13 at 18:09

3

As an alternative, you can use CompareValidator instead of RegularExpressionValidator. It goes like this:

<asp:CompareValidator ID="CompareValidator2" runat="server" ControlToValidate="txtIssueDate" ErrorMessage="Invalid Date Format" Type="Date" Operator="DataTypeCheck" Display="Dynamic" Text="*" ForeColor="Red" ValidationGroup="valGroup1"></asp:CompareValidator>

edited Nov 15 '13 at 18:09

Alan Moore

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answered Nov 15 '13 at 18:02

Yogi

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score 3 · Answer 5 · edited Nov 16 '11 at 06:31

3

The above regular expression is correct for dd/mm/yyyy format. the expression is

(^((((0[1-9])|([1-2][0-9])|(3[0-1]))|([1-9]))\x2F(((0[1-9])|(1[0-2]))|([1-9]))\x2F(([0-9]{2})|(((19)|([2]([0]{1})))([0-9]{2}))))$)

edited Nov 16 '11 at 06:31

Sathyajith Bhat

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answered Nov 16 '11 at 06:22

vishal

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score 2 · Answer 6 · edited Dec 23 '11 at 09:52

2

Kettenbach had a problem. His co-worker suggested using regexs. Kettenbach then had two problems.

As others have said, use DateTime.TryParse or DateTime.TryParseExact on a custom validator and save yourself the nightmare that is regex :)

edited Dec 23 '11 at 09:52

bluish

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answered Aug 31 '09 at 20:20

Sk93

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Regexes aren't inherently evil. They need to be used judiciously, though. They work great for a certain class of text parsing problems. – TrueWill Sep 01 '09 at 00:36
3

oh I never said they were evil, per say... But they are on a level with cats. – Sk93 Sep 01 '09 at 08:06
Please attribute the above statement to Jamie Zawinski. – jason Dec 17 '09 at 16:57

score 1 · Answer 7 · edited Aug 15 '12 at 15:51

1

Last answer is actually the correct way to do. Use DateTime.TryParse.

Example:

DateTime dt;
if(DateTime.TryParse(Textbox1.Text,out dt))
{
 Label1.Text = "Invalid date format";
}

edited Aug 15 '12 at 15:51

Shankar Narayana Damodaran

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answered Dec 17 '09 at 16:48

wwd

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TryParse actually returns true if the parse was successful, so your notification of invalid date format should be in the else of that condition. – Gabriel Espinoza Sep 01 '14 at 15:50

score 0 · Answer 8 · edited Dec 23 '11 at 09:52

0

This isn't really an answer, but couldn't you use DateTime.Parse or DateTime.TryParse to check that the date is correct?

Either that or use a DateTime control to make sure it's impossible to enter data that isn't a DateTime. There's lots of JavaScript out there on this subject.

edited Dec 23 '11 at 09:52

bluish

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answered Aug 31 '09 at 20:17

Blue Toque

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score 0 · Answer 9 · answered Nov 17 '13 at 08:14

0

We can use a CustomValidator and use the override the ServerValidate method to check the TryParse!

answered Nov 17 '13 at 08:14

Muhammedh

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Mavromatos Alexandros · Answer 10 · 2016-06-02T07:30:18.903

0

([0][1-9]|[1][0-9|][2][0-9]|[3][0-1])\/([0][1-9]|[1][0-2])\/[1-2][0-9][0-9][0-9]

for dd/mm/yyyy (year can be from 1000 to 2999)

or

(([0][1-9]|[2][0-9]|[3][0-1]|[1-9]|[1][0-9])/([0][1-9]|[1][0-2]|[1-9])/([1-2][0-9][0-9][0-9]|[0-9][0-9]))

which includes d/m/yy (e.g. 1/12/82)

edited Jun 02 '16 at 07:30

answered May 25 '16 at 11:31

Mavromatos Alexandros

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C# Regular Expression to validate a date?

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