From: Axel Schmalowsky <aschmalowsky@...>
Date: 2009-07-14T22:08:02+09:00
Subject: Re: a regex that does not contain comma

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David A. Black wrote:
> Hi --
>
> On Tue, 14 Jul 2009, Glenn Jackman wrote:
>
>>    case string
>>    when /,/       then puts "#{string.inspect} contains a comma"
>>    when /^[^,]*$/ then puts "#{string.inspect} has no comma"
>>    end
>
> That second regex, on its own, won't tell you the whole story:
>
>    string = <<-EOM
>    Hi.
>    I have, at a minimum, two commas.
>    Bye.
>    EOM
>
>    p "Match!" if /^[^,]*$/.match(string)
>      => Match!
>
Technically, the regexp above always succeeds (iirc).
Even though the regexp is delimited by ^ and $,
it matches always as along as the string against which the regexp is applied
does not consist of only a single comma ('[^,]* -- match everything
(including nothingness) but a comma).

So, I guess it's better to simply use /,/.


> You'd want to use \A and \z, rather than ^ and $ (which delimit lines,
> rather than the whole string).
>
> But if you've already tested for /,/, then you should be able just to
> have an else clause in your case statement, to cover cases where /,/
> didn't match.
>
>
> David
>


- --
Freundliche Gr��e / Kind regards

Axel Schmalowsky
Platform Engineer
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