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Re: problem re-search with the \| op.
From: |
Barry Margolin |
Subject: |
Re: problem re-search with the \| op. |
Date: |
Thu, 10 Jan 2008 22:35:34 -0500 |
User-agent: |
MT-NewsWatcher/3.5.3b2 (PPC Mac OS X) |
In article
<ce71df65-e69f-415b-8d7a-721782e4445f@d70g2000hsb.googlegroups.com>,
rtra <ruitra@gmail.com> wrote:
> Hi,
>
> I'm having problems searching for a regular expression matching two
> alternatives, A or B.
> A = "#title "
> B = "\* [A-Z][a-z]+.*"
> and allow '.' (dot) to be string concatenation
'.' is string concatenation in Perl, not Lisp. Lisp does everything
using functions, not operators like this. The string concatenation
function is concat.
>
> (re-search-backward A 1 t) matches the string A as I intended, and
> (re-search-backward B 1 t) also matches B as intended, but
> (re-search-backward A."\|".B 1 t) does not matches A or B as I thought
> it should
(re-search-backward (concat a "\\|" b) 1 t)
You need to escape the backslash because it has a special meaning in
strings.
>
> I'm using GNU Emacs 22.1.1, and testing this with a file like
> ----8<----
> #title test
> * tset
>
> <point is here>
> ----8<----
>
> Thank you for you time.
> (I've wasted some in the manual, but I'm not figuring this out...)
>
> Rui Almeida
--
Barry Margolin, barmar@alum.mit.edu
Arlington, MA
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