Solved : Regular Expression for MMYY

[Sagar Rohankar]

Hi All,

Is it possible for a string like Month and Year combination like this "MMYY" to be validated using Regular Expression ?

I try , but did`n succeed.
This my RE.

  ^[0-1][1-9][0-9][0-9]$  

Any Inputs ?

[ August 30, 2008: Message edited by: Sagar Rohankar ]
[ August 30, 2008: Message edited by: Sagar Rohankar ]

[Sagar Rohankar]

Sorry , but with some R&D I found a ggod soloution :

New RE for checking MMYY pattern

  ^0[1-9]|^(11)|^(12)[0-9][0-9]$  

[Campbell Ritchie]

Well done
[ August 30, 2008: Message edited by: Campbell Ritchie ]

[Piet Verdriet]

Originally posted by Sagar Rohankar:
Sorry , but with some R&D I found a ggod soloution :

New RE for checking MMYY pattern

  ^0[1-9]|^(11)|^(12)[0-9][0-9]$  

What about October?
Also note that the logical OR has a low precedence in regex, so your regex really means:

^0[1-9]
or
^(11)
or
^(12)[0-9][0-9]$

So, it would match "09" or "11" or "1208" but not "1108", for example.

Try this:

^(0[1-9]|1[0-2])[0-9][0-9]$

[ September 01, 2008: Message edited by: Piet Verdriet ]

[Rob Spoor]

Also, your code allows dates such as 1189.

I'd go for SimpleDateFormat with setLenient(false).
[ August 30, 2008: Message edited by: Rob Prime ]

[Piet Verdriet]

Originally posted by Rob Prime:
Also, your code allows dates such as 1189.

...

Assuming that 11-'89 is an invalid date for the OP...

[Rob Spoor]

Right, the last two digits are years, not days. My bad/

[Sagar Rohankar]

Originally posted by Piet Verdriet:



What about October?
Also note that since the logical OR has a low presedence in regex, so your regex really means:

^0[1-9]
or
^(11)
or
^(12)[0-9][0-9]$

So, it would match "09" or "11" or "1208" but not "1108",

Gotcha , Thanks Piet , I`m partying all day assuming I got some Regular Expression skills !
But , anyways Thanks to you and Rob !!

Originally posted by Piet Verdriet:
So, it would match "09" or "11" or "1208" but not "1108",

I think, The "1108" string works !

[Piet Verdriet]

Originally posted by Sagar Rohankar:


I think, The "1108" string works !

I think not!

String regex = "^0[1-9]|^(11)|^(12)[0-9][0-9]$";
String[] tests = {"09", "11", "1208", "1108"};
for(String t: tests) {
  System.out.println("'"+t+"' matches the regex? "+t.matches(regex));
}
 
// Output:
//   '09' matches the regex? true
//   '11' matches the regex? true
//   '1208' matches the regex? true
//   '1108' matches the regex? false

What you probably meant was this regex:

"^(0[1-9]|11|12)[0-9][0-9]$"

See how I rearranged the parenthesis? Of course, you will still miss years with October as the month. So this is the correct one:

"^(0[1-9]|10|11|12)[0-9][0-9]$"

which can be shortened to

"^(0[1-9]|1[0-2])[0-9][0-9]$"

as I suggested in a previous reply.

Good luck!
[ September 01, 2008: Message edited by: Piet Verdriet ]

[Sagar Rohankar]

Actually I`m using Struts validation framework , which maps the input fields to validation .xml element, like this :

 <form name="testForm">
            <field property="email" depends="required,email">
                <arg0 key="ForgetPassword.email"/>
            </field>
            <field property="creditCardNumber" depends="required,creditCard">
                <arg0 key="payment.creditcard"/>
            </field>
            <field property="expirationDate" depends="required,mask">
                <arg0 key="payment.creditcarddate"/>
                <var>
                    <var-name>mask</var-name>
                    <var-value>[B]^0[1-9]|^(11)|^(12)[0-9][0-9]$[/B]</var-value>
                </var>
            </field>
        </form>   

Here email, .., expirationDate are input fields on JSP page .[This form ultimately results in JavaScript code , which validate the input fields ]

and this code allow "number" > 12, (Which I don't want ) and Interestingly allowing "1108" , (Which supposed to be not valid as per your code) !

I changed the Regular Exp to "^(0[1-9]|1[0-2])[0-9][0-9]$" ..
[ September 01, 2008: Message edited by: Sagar Rohankar ]