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Posted by Rik on 06/14/06 11:55
Csaba Gabor wrote:
> Suppose I want to check that a string, $str, starts with at least the
> first 3 letters of a given word, say "delete". Can I do that
> compactly with a regular expression? The following are not my idea
> of compact:
>
> preg_match("/^del(|e|et|ete)\\b/i", $str)
> Quadratic in the length of the given word
>
>
> preg_match("/^del(e(t(e)?)?)?\\b/i", $str)
> Really now. But at least it's linear
>
Euhm, why at LEAST 3?
You don't seem to be using 'more' matches.
Or is this just a quick example?
Normally, I wouldn't use regexes for this. The way you made them is about as
compact as they get for this particular purpose.
if(substr($str,0,3) = substr($needle,0,3){
//code...
}
If you're trying to do what I think you want, maybe this is the code for
you:
$needle = 'delete';
preg_match("/^[a-z]+\b/i", $str,$match);
if(strlen($match[0])>=3 && $match[0]==substr($needle,0,strlen($match[0]))){
//code if it matches
}
By no means shorter, but a lot more versatile.
Grtz,
--
Rik Wasmus
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