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Posted by Rik Wasmus on 10/17/07 21:10
On Wed, 17 Oct 2007 22:50:59 +0200, <davranfor@gmail.com> wrote:
> On 17 oct, 20:20, "Rik Wasmus" <luiheidsgoe...@hotmail.com> wrote:
>> On Wed, 17 Oct 2007 21:59:49 +0200, <davran...@gmail.com> wrote:
>> > Hello
>>
>> > I need a regular expression that validate a list of numbers separated
>> > by "-" , numbers can not be greater than 999
>>
>> > Valid examples
>> > 0
>> > 12-455-01
>> > 1-9
>> > 125-32-155-45-45
>>
>> > Invalid examples
>> > -1
>> > 45-
>> > 1-45665456-4
>> > 12-45-
>> > -
>>
>> Hmmz, showing a 'best try' would be appreciated. However, I normally
>> can't
>> resist a good regex, so here it goes:
>>
>> '/^([1-9][0-9]?)?[0-9](-([1-9][0-9]?)?[0-9])*$/'
>>
>> Untested BTW. I've made 78-034-89 invalid, as a number should not start
>> with zero, unless it's only 1 zero. 't Would be simpler if it was valid,
>> your choice.
>
> works like a charm, can you explain the simple way without check zero
> at start?
>
'/^ # match start of string
[0-9]{1,3} # match 1 to 3 digits
( # start subpattern
- # literal -
[0-9]{1,3} # match 1 to 3 digits
)* # match subpattern zero or more times
$ # match has to run all the way up untill the end of the string
/x'
When starting with regexes, and certainly for the more complex ones, don't
underestimate the power of /x: comments in the regex itself, indentation
to keep things clear, it does wonders. It also keeps you from
rediscovering how the hell your regex worked 6 months after you wrote it
when you have to track a bug.....
--
Rik Wasmus
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