[vox-tech] Regexp question

[Ken Bloom]

Ken Herron wrote:
> Ken Bloom wrote:
> 
>> How can I match, in one regexp strings that begin with "att_" but do not
>> begin with "att_appraisal"?
> 
> 
> In perl or something with perl's regexp capabilities, you'd use a
> negative lookahead:
> 
>     ^att_(?!appraisal)

irb(main):001:0> "att_products".match(/^att_(?!appraisal)/)
=> #<MatchData:0xb7cf80c4>
irb(main):002:0> "att_appraisal".match(/^att_(?!appraisal)/)
=> nil

Works like a charm in Ruby. Thanks!

> Without that, your best bet is to combine two regexps using boolean logic:
> 
>     if (/^att_/ && !/^att_appraisal/)

This is what I changed it to before sending the message.

> You could do this with one regexp but it's ugly:
> 
>     ^att_($|[^a]|a($|[^p]|p($|[^p]|p($[^r]|...
> 
> i.e., "att_" followed by end-of-string OR not-a OR a followed by (end of
> string OR not-p OR p followed by..

I thought of that, but I *most definitely* wasn't going to try it.

Thanks

--Ken

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