[racket] Backreference question (regex)

From: Justin Phillips (jjustinphillipss at gmail.com)
Date: Fri Oct 29 17:36:47 EDT 2010

I have been using regexp-match
specifically --
(regexp-match "(1)\1" "112")
I'm 100% positive I'm missing some dorky character that will make this work.

On Fri, Oct 29, 2010 at 2:33 PM, Carl Eastlund <cce at ccs.neu.edu> wrote:

> I'm not sure I know what problem you're running into, but if you use
> Perl regular expression be sure to use (pregexp ...) to compile them
> or #px"..." to write them.  Otherwise you get a slightly different
> regular expression language (compatible with Unix utilities like
> egrep, rather than with Perl).  If you're using those regular
> expressions, they don't have backreferences.
> Carl Eastlund
> On Fri, Oct 29, 2010 at 5:29 PM, Justin Phillips
> <jjustinphillipss at gmail.com> wrote:
> > I'm trying to write a small regex that would return any repeating pattern
> in
> > a string e.g. ("ababcdcdababcdcd" would return "ab" "cd" abab" "cdcd"
> > "ababcdcd")
> > I'm having trouble using the backreferencing. I see under section 3.7.2
> of
> > the guide (and also some Perl docs I've checked out) that I should be
> able
> > to write a simple regex "(1)\1" which would return true for the data
> "113"
> > but Racket says I'm wrong. Any help would be greatly appreciated.
> > -Justin
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