Date regex dd/MM/yyy or yyyy

Question

I have a date field that takes a date with the "dd/MM/yyy" format or "yyyy". So I used this regex:

REGEX_DATE = "^((([0]{1}[1-9]{1})|([1-2]{1}[0-9]{1})|([3]{1}[0-1]{1}))"
            + "/(([0]{1}[1-9]{1})|([1]{1}[0-2]{1}))/([0-9]{4}))"
            + "|(([1]{1}([9]{1})[1-9]{1}[0-9]{1}))"
            + "|(([2]{1}([0-9]{3}))) "
            + "|^((([0]{1}[1-9]{1})|([1-2]{1}[0-9]{1})|([3]{1}[0-1]{1}))(([0]{1}[1-9]{1})|([1]{1}[0-2]{1}))([0-9]{4}))"
            + "|^$";

But the dates with the format "yyyy" are not working. Where is my mistake?

Thanks!

You do realize `{1}` is completely redundant and unnecessary, right? — jwodder, Jun 18 '15 at 15:28
It works fine for me. Is there a particular input that is not working? — Anonymous, Jun 18 '15 at 15:29
I would advise using http://stackoverflow.com/questions/43802/how-to-convert-a-date-string-to-a-date-or-calendar-object instead of regex for this. — Rossiar, Jun 18 '15 at 15:29
I don't know if it's a typo, but is that meant to be a 3-digit year? `dd/MM/yyy`? — Mr. Llama, Jun 18 '15 at 15:30
"are not working" is a bit vague. can you provide some examples that should be matched but aren't? — fferri, Jun 18 '15 at 15:32
`[0]{1}`, `[1]{1}`, and `[2]{1}` are confabulated ways to ask for "just a single `0`, `1`, and `2`". Making a regex overly complicated is one way to ensure no-one else can modify it. Also consider using `\d` instead of `[0-9]`. — Jongware, Jun 18 '15 at 15:34
@Chris - Are you trying to *parse* a date, or *validate* a date? Either way, its probably better to use a language built-in instead of regex. — Mr. Llama, Jun 18 '15 at 15:38

score 0 · Accepted Answer · answered Jun 18 '15 at 15:29

0

Can't you use this:

((0[0-9]|1[0-2])\/([0-2][0-9]|3[0-1])\/)?\d{4}

answered Jun 18 '15 at 15:29

jcuenod

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Date regex dd/MM/yyy or yyyy

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