Regex Specific Date Format

Question

I was wondering if somebody could point me to a regex code that validates for this: ####/##/##

Example: 1990/05/25

The second number 0 can only be 0 or 1 and the number 2 and only be 0, 1, 2, or 3. Other than that all other numbers in this set are allowed (0-9).

The code should validate that there is only 9 or 10 characters in total including the slashes.

Do you only want to validate the string or also validate the date itself? For instance, `2013/02/29` is not a valid date. Also, very important: what (programming) language are you using? — Jerry, May 29 '13 at 13:13
Do you mean the character in position 0 can only be 0 or 1 and character in position 2 can only be 0,1,2 or 3? — Norman H, May 29 '13 at 13:15
@Jerry Well yes I am basically validating that it is a date in this format 2013/05/29 If its possible I I would prefer if it also allows 2013/5/29 — Bagzli, May 29 '13 at 13:15
@Norman The character with number 0 - Sorry should of been more specific — Bagzli, May 29 '13 at 13:16

score 3 · Accepted Answer · edited May 23 '17 at 10:25

3

If you only want to validate this format, you can use a regex like...

^\d{1,4}\/[01]?\d\/[0-3]\d$

I tested it a bit on some dates here.

This will match:

But reject:

23121/32/44
12/05/013
013/000/00

If you want to reject invalid dates as well such as 2013/02/29, you can check out this thread.

edited May 23 '17 at 10:25

Community

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answered May 29 '13 at 13:18

Jerry

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12235/23/2/ passed the validation. So it can't serve my purpose :( – Bagzli May 29 '13 at 13:23
@Bagzli Did you include the anchors (`^` and `$`)? I added them a bit later. – Jerry May 29 '13 at 13:24
Thank you, I tried the new code and it seems to validate for all bad cases I can think of. I think I used your old code when I tried it the first time. – Bagzli May 29 '13 at 13:36
@Bagzli Yes, sorry about that, I wasn't thinking that you might have extra characters before and after the date initially. ^^; Glad that I was able to help! – Jerry May 29 '13 at 13:37

Bathsheba · Answer 2 · 2013-05-29T13:32:40.413

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Try this (edit following Jerry)

[0-2][0-9]{3,3}/[0|1][0-9]/[0-3][0-9]

Mess about with the {a,b} notation to change the length of the general digits, it means between a and b of the preceding expression inclusive. It's unclear in your question where you want the digit flexibility to be.

E.g. to emit 2013/5/29, use

 [0-2][0-9]{3,3}/[0|1]{0,1}[0-9]/[0-3][0-9]

edited May 29 '13 at 13:32

answered May 29 '13 at 13:18

Bathsheba

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I tried typing this in: 12235/23/2/ and it said it is valid. I really need it to check that the code is 9 or 10 digits long and to only allow specific numbers in certain spots as described in my question. – Bagzli May 29 '13 at 13:21
That fails on my regex parser (Boost C++) using either regex I've given. Which parser are you using? – Bathsheba May 29 '13 at 13:22
using this on asp.net (c#) ValidationSummary with CustomValidator – Bagzli May 29 '13 at 13:30
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@Bathsheba This will not allow any year after 1999, like 2000 or 2013 because of the `[0|1]` at the start :(. Also, `[01]` is the same as `[0|1]`. – Jerry May 29 '13 at 13:31
I don't think your regex parser is doing what you want it to do. Why not test it with something simple like [0-9]? i.e. one digit. – Bathsheba May 29 '13 at 13:31

score 1 · Answer 3 · answered May 29 '13 at 13:22

For all things regex I have found this website to be an invaluable resource. http://www.regular-expressions.info/reference.html

Specifically this page should get you what you need and contains a full explanation of how to go about validating date input format (not value) via Regular Expressions.

http://www.regular-expressions.info/dates.html

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

would match

yyyy-mm-dd

Regex Specific Date Format

3 Answers3

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