From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Jean Louis Newsgroups: gmane.emacs.help Subject: Re: Is there any difference between `equal' and `string=' for strings? Date: Sat, 21 Aug 2021 12:04:08 +0300 Message-ID: References: <875yw2vxqh.fsf@mbork.pl> <87v941domi.fsf@zoho.eu> <87tujkd46u.fsf@zoho.eu> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="31920"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Mutt/2.0.7+183 (3d24855) (2021-05-28) To: help-gnu-emacs@gnu.org Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Sat Aug 21 11:05:42 2021 Return-path: Envelope-to: geh-help-gnu-emacs@m.gmane-mx.org Original-Received: from lists.gnu.org ([209.51.188.17]) by ciao.gmane.io with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1mHMwg-00082c-3G for geh-help-gnu-emacs@m.gmane-mx.org; Sat, 21 Aug 2021 11:05:42 +0200 Original-Received: from localhost ([::1]:50756 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mHMwe-0000uA-CZ for geh-help-gnu-emacs@m.gmane-mx.org; Sat, 21 Aug 2021 05:05:40 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:57538) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mHMw1-0000tw-Ja for help-gnu-emacs@gnu.org; Sat, 21 Aug 2021 05:05:01 -0400 Original-Received: from stw1.rcdrun.com ([217.170.207.13]:48815) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mHMvz-0001Vt-Vn for help-gnu-emacs@gnu.org; Sat, 21 Aug 2021 05:05:01 -0400 Original-Received: from localhost ([::ffff:154.230.162.245]) (AUTH: PLAIN admin, TLS: TLS1.3,256bits,ECDHE_RSA_AES_256_GCM_SHA384) by stw1.rcdrun.com with ESMTPSA id 0000000000069CB5.000000006120C1B8.00004984; Sat, 21 Aug 2021 02:04:56 -0700 Mail-Followup-To: help-gnu-emacs@gnu.org Content-Disposition: inline In-Reply-To: <87tujkd46u.fsf@zoho.eu> Received-SPF: pass client-ip=217.170.207.13; envelope-from=bugs@gnu.support; helo=stw1.rcdrun.com X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: help-gnu-emacs@gnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Users list for the GNU Emacs text editor List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Original-Sender: "help-gnu-emacs" Xref: news.gmane.io gmane.emacs.help:132642 Archived-At: * Emanuel Berg via Users list for the GNU Emacs text editor [2021-08-20 09:25]: > Jean Louis wrote: > > > How I understand it, it is good also for comparison of > > symbols as strings. > > > > (setq s1 "Jane") -> "Jane" > > (setq s2 "Jane") -> "Jane" > > (setq s3 "Doe") -> "Doe" > > > > Then this is how I understand the intended purpose: > > > > (string= s1 s2) -> t > > (string= s1 s3) -> nil > > Uhm, but in that case, s1, s2, and s3 are evaluated to their > string values, so at the time of `string=', that's > > (string= "Jane" "Jane") ; t > (string= "Jane" "Doe" ) ; nil Yes, that is what I meant. It is good to compare symbols which are possibly strings if they are equal to each other. (setq s1 1) ⇒ 1 (setq s2 "1") ⇒ "1" Which is also good to show the error if one of symbols is not string: (string= s1 s2) eval: Wrong type argument: stringp, 1 > > And of course you are free to compare empty symbols: > > > > (string= 'hi 'hi) -> t > > With symbols their "print names" are used, you can get that > with > > (symbol-name 'hi) ; "hi" > > So that's virtually (string= "hi" "hi") only here it is done > _by_ and not before string= (as 'hi does not evaluate to the > string "hi", for example). That I don't understand, what I know is that `string=' will evaluate symbols as strings and compare them, interesting is it will accept `nil' as value: (setq s1 "1") ⇒ "1" (setq s2 "1") ⇒ "1" (string= s1 s2) ⇒ t (setq s1 "1") ⇒ "1" (setq s2 nil) ⇒ nil (string= s1 s2) ⇒ nil -- Jean Take action in Free Software Foundation campaigns: https://www.fsf.org/campaigns In support of Richard M. Stallman https://stallmansupport.org/