Regex validate date and month

Question

I'm trying to validate the date and month in below format:

MM/dd

And now, I'm using this regex to validate:

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

And the regex successfully validate these formats:

    //Below are valid dates    
    09/05
    01/01
    12/30
    10/30
    //Below are invalid dates
    11/31
    09/31

How to modify the regex so that it also checks the days in month?

How come `12/31` is invalid? Dec 31? – Wiktor Stribiżew Apr 20 '15 at 07:57 — Wiktor Stribiżew, Apr 20 '15 at 07:57
Oh, sorry, I changed the date to 11/31 instead... – User2012384 Apr 20 '15 at 07:58 — User2012384, Apr 20 '15 at 07:58

Soner Gönül · Accepted Answer · 2015-04-20T08:05:30.900

4

I don't think regex is the right way to do this. Use DateTime parsing instead with MM/yy format and a culture that have / as a DateSeparator.

string s = "12/31";
DateTime dt;
if(DateTime.TryParseExact(s, "MM/dd", CultureInfo.InvariantCulture,
                          DateTimeStyles.None, out dt))
{
    // Valid
}

By the way, September and November have 30 days, not 31. That's why 09/31 and 11/31 are invalid.

edited Apr 20 '15 at 08:05

answered Apr 20 '15 at 07:57

Soner Gönül

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Regex validate date and month

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