From: Shadowfirebird <shadowfirebird@...>
Date: 2008-08-13T17:14:32+09:00
Subject: Re: regular expresson isue

Sorry to be the awkward one, but maybe you should consider handling
this programatically, rather than in a regex?

Pros: your code is likely to be easier to understand: that makes it
more maintainable.
Cons: your code will be longer.




On Wed, Aug 13, 2008 at 3:40 AM, Peņa, Botp <botp@delmonte-phil.com> wrote:
> From: Raj Singh [mailto:neeraj.jsr@gmail.com]
> # ([0-9]|0[0-9]|1[012]):([0-9]|0[0-9]|[1-5][0-9])\s*(am|pm)
> # I don't want this regext to match 13:45 PM because the the numerical
> # value before the colon should be limited to 12. How to fix it?
>
> Hi Raj,
>
> the 13 is matching
>
>  ([0-9]|0[0-9]|1[012])
>   ^^^^^
>   this
>
> because the regex will match the 3. the regex did not care if it had a 1 before it.
>
> You may want to tell it to not match any preceding digit (or else it be a beginning of the string) if you want a stand alone digit.
> eg, you may want to achor/prefix it w the ^ (for beginning of string)
> or \D (to represent a non-digit character)
>
> sample tests,
>
> irb(main):112:0> re = /((^|\D)[0-9]|0[0-9]|1[012]):/
> => /((^|\D)[0-9]|0[0-9]|1[012]):/
>
> irb(main):113:0> re  =~ "1:"
> => 0
> irb(main):114:0> re  =~ " 1:"
> => 0
> irb(main):117:0> re  =~ "13:"
> => nil
>
> irb(main):122:0> re  =~ "01:"
> => 0
> irb(main):123:0> re  =~ "11:"
> => 0
> irb(main):124:0> re  =~ "12:"
> => 0
>
> kind regards -botp
>



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