Regex to validate date format dd/mm/yyyy

Question

I need to validate a date string for the format dd/mm/yyyy with a regular expresssion.

This regex validates dd/mm/yyyy, but not the invalid

Answer 1

I'm working with an API that only accepts MM/DD/YYYY format. I couldn't find any other post that did leap years quite as well as Ofir's answer, so I tweaked it and am re-posting it here for anyone that might need it.

/^(?:(?:(?:0[13578]|1[02])(\/)31)\1|(?:(?:0[1,3-9]|1[0-2])(\/)(?:29|30)\2))(?:(?:1[6-9]|[2-9]\d)?\d{2})$|^(?:02(\/)29\3(?:(?:(?:1[6-9]|[2-9]\d)?(?:0[48]|[2468][048]|[13579][26])|(?:(?:16|[2468][048]|[3579][26])00))))$|^(?:(?:0?[1-9])|(?:1[0-2]))(\/)(?:0[1-9]|1\d|2[0-8])\4(?:(?:1[6-9]|[2-9]\d)?\d{2})$/

Answer 2

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

will validate any date between 1900-2099

Answer 3

I know it is a tangential answer to the question, but if the intention of the question is 'how do I validate a date?', then why not try letting the programming language do all the hard work (if you are using a language that can)?

e.g. in php

$this_date_object = date_create($this_date);

if ($this_date_object == false )
    {

        // process the error

    }

Answer 4

Here is another version of regex to match any of the following date formats and allow leading zeros to be omitted:

Regex: ^[0-3]?[0-9].[0-3]?[0-9].(?:[0-9]{2})?[0-9]{2}$

Matches:

1/1/11 or 1.1.11 or 1-1-11 : true 01/01/11 or 01.01.11 or 01-01-11 : true 01/01/2011 or 01.01.2011 or 01-01-2011 : true 01/1/2011 or 01.1.2011 or 01-1-2011 : true 1/11/2011 or 1.11.2011 or 1-11-2011 : true 1/11/11 or 1.11.11 or 1-11-11 : true 11/1/11 or 11.1.11 or 11-1-11 : true

Debuggex Demo

Answer 5

For those who look at these and get completely confused, here is an excerpt from my script. Unfortunately, all it does is match valid numbers in a date time input, and 31st Feb will be marked as valid, but as so many have said, regex really isn't the best tool to do this test.

To match a date in the format 'yyyy-MM-dd hh:mm' (Or indeed in whatever order you please)

var dateerrors = false;
var yearReg = '(201[4-9]|202[0-9])';            ///< Allows a number between 2014 and 2029
var monthReg = '(0[1-9]|1[0-2])';               ///< Allows a number between 00 and 12
var dayReg = '(0[1-9]|1[0-9]|2[0-9]|3[0-1])';   ///< Allows a number between 00 and 31
var hourReg = '([0-1][0-9]|2[0-3])';            ///< Allows a number between 00 and 24
var minReg = '([0-5][0-9])';                    ///< Allows a number between 00 and 59
var reg = new RegExp('^' + yearReg + '-' + monthReg + '-' + dayReg + ' ' + hourReg + ':' + minReg + '$', 'g');
$('input').filter(function () {return this.id.match(/myhtml_element_with_id_\d+_datetime/);}).each(function (e) {
    if (e > 0) {
        // Don't test the first input. This will use the default
        var val = $(this).val();
        if (val && !val.trim().match(reg)) {
            dateerrors = true;
            return false;
        }
    }
});
if (dateerrors) {
    alert('You must enter a validate date in the format "yyyy-mm-dd HH:MM", e.g. 2019-12-31 19:30');
    return false;
}

The above script starts off by building a regex object. It then finds all of the inputs whose id's match a certain pattern and then loops through these. I don't test the first input I find (if (e > 0)).

A bit of explanation:

var reg = new RegExp('^' + yearReg + '-' + monthReg + '-' + dayReg + ' ' + hourReg + ':' + minReg + '$', 'g');

^ means start of match, whereas $ means end of match.

return this.id.match(/myhtml_element_with_id_\d+_datetime/);

\d+ means match a single or a contiguous sequence of integers, so myhtml_element_with_id_56_datetime and myhtml_element_with_id_2_datetime will match, but myhtml_element_with_id_5a_datetime will not

Answer 6

Found this reg ex here

^(((0[1-9]|[12]\d|3[01])\/(0[13578]|1[02])\/((19|[2-9]\d)\d{2}))|((0[1-9]|[12]\d|30)\/(0[13456789]|1[012])\/((19|[2-9]\d)\d{2}))|((0[1-9]|1\d|2[0-8])\/02\/((19|[2-9]\d)\d{2}))|(29\/02\/((1[6-9]|[2-9]\d)(0[48]|[2468][048]|[13579][26])|((16|[2468][048]|[3579][26])00))))$

This validates the format mm/dd/yyyy and valid dates correctly (but not m/d/yyyy).

Some tests