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Re: Quickie - Regexp for a string not at the beginning of the line


From: Rivka Miller
Subject: Re: Quickie - Regexp for a string not at the beginning of the line
Date: Thu, 25 Oct 2012 21:45:05 -0700 (PDT)
User-agent: G2/1.0

Thanks everyone, esp this gentleman.

The solution that worked best for me is just to use a DOT before the
string as the one at the beginning of the line did not have any char
before it. I guess, this requires the ability to ignore the CARAT as
the beginning of the line.

I am a satisfied custormer. No need for returns. :)

On Oct 25, 7:11 pm, Ben Bacarisse <address@hidden> wrote:
> Rivka Miller <address@hidden> writes:
> > On Oct 25, 2:27 pm, Danny <address@hidden> wrote:
> >> Why you just don't give us the string/input, say a line or two, and
> >> what you want off of it, so we can tell better what to suggest
>
> > no one has really helped yet.
>
> Really?  I was going to reply but then I saw Janis had given you the
> answer.  If it's not the answer, you should just reply saying what it is
> that's wrong with it.
>
> > I want to search and modify.
>
> Ah.  That was missing from the original post.  You can't expect people
> to help with questions that weren't asked!  To replace you will usually
> have to capture the single preceding character.  E.g. in sed:
>
>   sed -e 's/\(.\)$hello\$/\1XXX/'
>
> but some RE engines (Perl's, for example) allow you specify zero-width
> assertions.  You could, in Perl, write
>
>   s/(?<=.)\$hello\$/XXX/
>
> without having to capture whatever preceded the target string.  But
> since Perl also has negative zero-width look-behind you can code your
> request even more directly:
>
>   s/(?<!^)\$hello\$/XXX/
>
> > I dont wanna be tied to a specific language etc so I just want a
> > regexp and as many versions as possible. Maybe I should try in emacs
> > and so I am now posting to emacs groups also, although javascript has
> > rich set of regexp facilities.
>
> You can't always have a universal solution because different PE
> implementations have different syntax and semantics, but you should be
> able to translate Janis's solution of matching *something* before your
> target into every RE implementation around.
>
> > examples
>
> > $hello$ should not be selected but
> > not hello but all of the $hello$ and $hello$ ... $hello$ each one
> > selected
>
> I have taken your $s to be literal.  That's not 100 obvious since $ is a
> common (universal?) RE meta-character.
>
> <snip>
> --
> Ben.



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