Go Premium for a chance to win a PS4. Enter to Win


Date input validation (Regular Expressions) [2]

Posted on 2016-11-27
Medium Priority
Last Modified: 2016-11-27
I had this question after viewing Date input validation (Regular Expressions).

Hi guys,
I have expression below :

Open in new window

1. Day validation of 28, 29, 30, 31
2. years in range 1800-2099
3. seperator /
4. format dd/mm/yyyy

I tied to fix days and months in range   1, 2, 3, 4, . . .  or  01, 02, 03, 04, . . .

validation is successful on any month and any year (include leap year)
Except these entries on February: 1/2/2016, 2/02/2016, 3/2/2017 . . .  Failure on one digit day.

 Thank you!
Question by:Darius
  • 2
  • 2
LVL 19

Expert Comment

by:Kim Ryan
ID: 41903389
Looks like you just left out the ? after 0 day in February, line 6 in the Perl example below
my $a = '2/02/2016';

if ($a =~ /^
    ((0?[1-9]|[12][0-9]|3[01])[\/](0?[13578]|1[02])[\/](18|19|20)[0-9]{2})|  # jan, march, may etc
    ((0?[1-9]|[12][0-9]|30)[\/](0?[469]|11)[\/](18|19|20)[0-9]{2})|          # apr, jun etc
    ((0?[1-9]|1[0-9]|2[0-8])[\/](0?[2])[\/](18|19|20)[0-9]{2})|              # feb
    (29[\/](0?[2])[\/](((18|19|20)(04|08|[2468][048]|[13579][26]))|2000))$   # leap day
    /x )
    print "matched day: $1\n";

Open in new window

There are plenty of lubraries to do this type of validation: Date::Parse

Author Comment

ID: 41903399
Hi Kim,

  I have the same changes done, but it brake February validation

For example:  29/2/2017,  29/02/2017,  29/2/2018,  29/02/2018, 29/2/2019,  29/02/2019, . . .

Leap year 2016, 2020, . . .  correct!

LVL 19

Accepted Solution

Kim Ryan earned 2000 total points
ID: 41903459
The anchors point ^ and $ didn't seem to be working, they need to be inside brackets.

    ((^0?[1-9]|[12][0-9]|3[01])[\/](0?[13578]|1[02])[\/](18|19|20)[0-9]{2})$|  # jan, march, may etc
    ((^0?[1-9]|[12][0-9]|30)[\/](0?[469]|11)[\/](18|19|20)[0-9]{2})$|          # apr, jun etc
    ((^0?[1-9]|1[0-9]|2[0-8])[\/](0?[2])[\/](18|19|20)[0-9]{2})$|              # feb
    $))   # leap day

Open in new window

This would be a lot simpler if you just extracted dd, mm, yyyy and then used if then logic to validate all cases (such as is year divisible by 4 but not 400 etc).

Author Comment

ID: 41903468

This is just a challenge for myself. Thanks for help!

Featured Post

Free Tool: Port Scanner

Check which ports are open to the outside world. Helps make sure that your firewall rules are working as intended.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

by Batuhan Cetin Regular expression is a language that we use to edit a string or retrieve sub-strings that meets specific rules from a text. A regular expression can be applied to a set of string variables. There are many RegEx engines for u…
We are witnesses that everyone is saying that our children shouldn't "play" with a technology because it is dangerous. This article is going to prove that they are wrong.
Learn how to match and substitute tagged data using PHP regular expressions. Demonstrated on Windows 7, but also applies to other operating systems. Demonstrated technique applies to PHP (all versions) and Firefox, but very similar techniques will w…
Explain concepts important to validation of email addresses with regular expressions. Applies to most languages/tools that uses regular expressions. Consider email address RFCs: Look at HTML5 form input element (with type=email) regex pattern: T…
Suggested Courses

885 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question