On Thu, 27 Jan 2005 16:56:05 +0100, Zouari Fourat <fourat@xxxxxxxxx> wrote:
> > this is working fine :
> > if (eregi("^-?([1-3])+$",$x)
> > echo "x is 1 or 2 or 3";
>
> i forgot to say that doesnt work with 1-20 :(
> how to do it ?
You're far better off doing it arithmetically as someone already said,
however if you absolutely *have* to use a regexp then this is how you
go about it:
You need to match these possible variations:
1. the number '20'
2. the number '1' followed by any digit between 0 and 9.
3. any digit between 1 and 9.
the pattern for the first one is easy. it's just a fixed string: 20
the pattern for the second is only slightly harder: 1[0-9]
the pattern for the third is: [1-9]
You want to match any of them, so you join them together with an
alternation operator, the '|' symbol to get: 20|1[0-9]|[1-9]
This will match any string that contains the numbers 1-20, such as
'200'. To make sure it only matches exactly the numbers you're
interested in, you have to "anchor" the start and finish ending up
with this:
if (preg_match('/^(20|1[0-9]|1-9])$/', $candidate)) {
// $candidate is a decimal integer between 1 and 20 inclusive with
no leading zeros.
}
-robin
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