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 Posted by frizzle on 07/16/06 15:25 
Rik wrote: 
> Rik wrote: 
> > $regex ='/    #opening delimiter 
> >     ^    #start of string 
> >         (?:    #start of non-capturing group 
> >                 [a-z]  #any character between a and z 
> >             |       #OR 
> >                 (?<=   #start of positive lookbehind (is preceeded 
> >                     by..) [a-z]    #any character between a and z 
> >                 )      #end of positive lookbehind 
> >                 [-_]   #character - or _ (not incorrect, but probably 
> > better to [_\-],[_-] or [\-_] 
> >                 (?=    #start of positive lookahead 
> >                     [a-z]    #any character between a and z 
> >                 )      #end of positive lookahead 
> >         )     #end of non-capturing group 
> >         +    #1 or more times, greedy 
> >     $    #end of string 
> > /x'; 
> > 
> 
> 
> It just occured to me that, allthough a wonderfull example: 
> 
> $regex ='/^(?:[a-z]|[a-z][_\-][a-z])+$/'; 
> 
> ...will do just fine. 
> 
> equally so: 
> $regex ='/^(?:[a-z]+(?:[_\-][a-z]+))+$/'; 
> 
> Lookahead & -behind are unneccessary in this case, and this keep it simple. 
> 
> Grtz, 
> -- 
> Rik Wasmus 
 
Wow, thanks for the explanation! 
Nice link there as well. Going right into my bookmarks. 
 
Frizzle.
 
  
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