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From: munson@renoir.Berkeley.EDU (Ethan V. Munson)
Newsgroups: gnu.emacs
Subject: Help with backslashes
Message-ID: <27258@ucbvax.BERKELEY.EDU>
Date: 27 Dec 88 20:21:44 GMT
Sender: usenet@ucbvax.BERKELEY.EDU
Reply-To: munson@renoir.Berkeley.EDU (Ethan V. Munson)
Distribution: gnu
Organization: University of California, Berkeley
Lines: 28

I need some help with defining constants to be used later for regular
expression searches.  Suppose I want to search for strings beginning
with an @ sign followed by optional whitespace and then string of 
alpha characters.  I would expect to use something like:

(defconst re1 "@\\s *\\([a-z]*\\)\\1")

Note that I am using parentheses to pull out substrings.  Given this
Lisp sexp, GNU Emacs version 18.51.9 gives the symbol re1 the value:

	"@\\s *\\([a-z]*\\)\\1"

I didn't expect this.  I thought Lisp reader would strip out one
backslash from each pair.  So, when I change the definition to

(defconst re1 "@\s *\([a-z]*\)\1")

the result is 

	"@s *([a-z])1"

Neither of these results is a regular expression that does what I want.
I have to admit that I am clueless about how to solve this in a
straightforward manner.  Does anyone see what I am doing wrong?

Ethan Munson
munson@renoir.Berkeley.EDU
...ucbvax!renoir!munson