[External] : Use the characters "+" and "-" in regular expressions

[steve-humphreys]

I wonder why I am getting 

Symbol's value as variable is void: message

(message " ")
(message "*** ***")
(setq s (string-match "[+]+"  "++++++++++++++++"))
message("%s" s)
(setq s (string-match "[+-]+" "++++++++++++++++"))
message("%s" s)
(setq s (string-match "[+-]+" "----------------"))
message("%s"  s)
 
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> > Sent: Thursday, May 20, 2021 at 9:59 AM
> > From: "Drew Adams" <drew.adams@oracle.com>
> > To: "tomas@tuxteam.de" <tomas@tuxteam.de>, "help-gnu-emacs@gnu.org" 
> > <help-gnu-emacs@gnu.org>
> > Subject: RE: [External] : Re: Use the characters "+" and "-" in regular 
> > expressions
> >
> > > Hm. According to the docs, the dash should go last, but 
> > > a test actually confirms that it works in first position.
> > 
> > I quoted this from (elisp) `Regexp Special':
> > 
> >    To include a ‘-’, write ‘-’ as the first or last
> >                                       ^^^^^^^^^^^^^
> >    character of the character alternative, or as the
> >    upper bound of a range.  Thus, ‘[]-]’ matches both
> >    ‘]’ and ‘-’.
> > 
> > That's from Emacs 26 (and all prior releases, at least
> > as far back as Emacs 20).  But yes, they changed that
> > text for Emacs 27, to this:
> > 
> >    To include ‘-’, put it at the end.
> >                           ^^^^^^^^^^
> > ___
> > 
> > For Emacs 20, it says this:
> > 
> >    To include a `-', write `-' as the first or last
> >    character of the character alternative, or put it
> >    after a range.  Thus, `[]-]' matches both `]' and
> >    `-'.
> >
> 
>