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Re: two's complement idea

From David Brown <david.brown@hesbynett.no>
Newsgroups comp.lang.c++
Subject Re: two's complement idea
Date 2020-01-25 19:55 +0100
Organization A noiseless patient Spider
Message-ID <r0i2ul$kig$1@dont-email.me> (permalink)
References (6 earlier) <4hBWF.107660$LY2.60603@fx23.am4> <slrnr2ma6t.km3.grahn+nntp@frailea.sa.invalid> <ZVFWF.603350$GFe.375230@fx12.am4> <slrnr2mqv7.km3.grahn+nntp@frailea.sa.invalid> <r0gfuo$5aa$1@dont-email.me>

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On 25/01/2020 05:24, James Kuyper wrote:
> On 1/24/20 5:12 PM, Jorgen Grahn wrote:
>> On Fri, 2020-01-24, Bart wrote:
> ...
>>> I can't see much in C++ that would eliminate the use-cases for goto in C.
>>
>> Of course not -- how could a feature in language X eliminate the need
>> for another feature in language Y?
> 
> I suspect he meant "I can't see much in C++ that would eliminate, in
> C++, the use-cases that, in C, justify the use of goto."
> 
> The only reasonably plausible justifications I've seen for using "goto"
> are for error handling, and the kind of error handling that justifies
> using "goto" is handled somewhat more easily in C++ by using exceptions,
> but I'm not at all surprised if Bart can't see that.
> 

"goto" is not used in C for error handling as such - it is used to 
handle deallocation of resources in the face of abnormal program flow 
(such as in the case of an error, but possibly from other situations). 
And the way this is handled in C++ is not exceptions - it is RAII. 
Exceptions are used to be able to pass control to a separate block with 
little source code needed in between - thus letting you have error 
handling without having to write the error handling manually in the code 
that could have an error.


So in C, people (not everyone, but some people write) :

	Get resource 1
	if (failed) goto exit
	if (leave early) goto release1
	Get resource 2
	if (failed) goto release1
	if (leave early) goto release2

	Use resource 1 and resource 2

release2:
	Release resource 2
release1:
	Release resource 1
exit:
	return


In C++, you can write:

	auto r1 = Get resource 1
	if (failed or leave early) return
	auto r2 = Get resource 2
	if (failed or leave early) return
	Use resource 1 and resource 2
	return

You can use early return, break, exceptions, goto, or whatever you want 
to leave the code block.  It is the /RAII/ that avoids the "goto" and 
labels collections needed to handle leak-free early exit, not exceptions.

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Thread

Re: two's complement idea Tim Rentsch <tr.17687@z991.linuxsc.com> - 2019-11-28 12:19 -0800
  Re: two's complement idea "Alf P. Steinbach" <alf.p.steinbach+usenet@gmail.com> - 2019-11-29 00:14 +0100
    Re: two's complement idea David Brown <david.brown@hesbynett.no> - 2019-11-29 09:15 +0100
      Re: two's complement idea Bo Persson <bo@bo-persson.se> - 2019-11-29 10:58 +0100
        Re: two's complement idea David Brown <david.brown@hesbynett.no> - 2019-11-29 12:49 +0100
    Re: two's complement idea Tim Rentsch <tr.17687@z991.linuxsc.com> - 2019-12-07 07:53 -0800
      Re: two's complement idea Öö Tiib <ootiib@hot.ee> - 2019-12-07 08:22 -0800
        Re: two's complement idea Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-01-10 20:44 -0800
          Re: two's complement idea Öö Tiib <ootiib@hot.ee> - 2020-01-10 23:44 -0800
            Re: two's complement idea Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-01-14 07:08 -0800
              Re: two's complement idea Öö Tiib <ootiib@hot.ee> - 2020-01-14 08:42 -0800
                Re: two's complement idea Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-01-21 02:09 -0800
                Re: two's complement idea James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-01-21 05:14 -0800
                Re: two's complement idea Daniel <danielaparker@gmail.com> - 2020-01-21 13:08 -0800
                Re: two's complement idea James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-01-22 00:07 -0500
                Re: two's complement idea Öö Tiib <ootiib@hot.ee> - 2020-01-21 23:21 -0800
                Re: two's complement idea Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-01-22 01:51 -0800
                Re: two's complement idea David Brown <david.brown@hesbynett.no> - 2020-01-22 11:28 +0100
                Re: two's complement idea Bonita Montero <Bonita.Montero@gmail.com> - 2020-01-22 11:52 +0100
                Re: two's complement idea Öö Tiib <ootiib@hot.ee> - 2020-01-22 04:47 -0800
                Re: two's complement idea Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-04-02 07:19 -0700
                Re: two's complement idea James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-04-02 08:07 -0700
                Re: two's complement idea boltar@nowhere.org - 2020-01-21 16:44 +0000
                Re: two's complement idea Jorgen Grahn <grahn+nntp@snipabacken.se> - 2020-01-21 20:01 +0000
                Re: two's complement idea boltar@nowhere.org - 2020-01-22 11:26 +0000
                Re: two's complement idea Christian Gollwitzer <auriocus@gmx.de> - 2020-01-22 20:04 +0100
                Re: two's complement idea Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-01-22 11:30 -0800
                Re: two's complement idea Chris Vine <chris@cvine--nospam--.freeserve.co.uk> - 2020-01-22 19:57 +0000
                Re: two's complement idea Ian Collins <ian-news@hotmail.com> - 2020-01-23 10:03 +1300
                Re: two's complement idea boltar@nowhere.org - 2020-01-23 09:24 +0000
                Re: two's complement idea Ian Collins <ian-news@hotmail.com> - 2020-01-24 07:29 +1300
                Re: two's complement idea Ian Collins <ian-news@hotmail.com> - 2020-01-23 10:03 +1300
                Re: two's complement idea "Fred. Zwarts" <F.Zwarts@KVI.nl> - 2020-01-23 10:09 +0100
                Re: two's complement idea boltar@nowhere.org - 2020-01-23 09:29 +0000
                Re: two's complement idea Bart <bc@freeuk.com> - 2020-01-24 01:08 +0000
                Re: two's complement idea boltar@nowhere.org - 2020-01-24 12:27 +0000
                Re: two's complement idea Bart <bc@freeuk.com> - 2020-01-24 01:06 +0000
                Re: two's complement idea Bo Persson <bo@bo-persson.se> - 2020-01-24 10:07 +0100
                Re: two's complement idea Paavo Helde <myfirstname@osa.pri.ee> - 2020-01-24 11:36 +0200
                Re: two's complement idea Öö Tiib <ootiib@hot.ee> - 2020-01-24 17:34 -0800
                Re: two's complement idea Siri Cruise <chine.bleu@yahoo.com> - 2020-01-24 17:57 -0800
                Re: two's complement idea Bart <bc@freeuk.com> - 2020-01-24 12:19 +0000
                Re: two's complement idea Bo Persson <bo@bo-persson.se> - 2020-01-24 14:19 +0100
                Re: two's complement idea Bart <bc@freeuk.com> - 2020-01-24 14:11 +0000
                Re: two's complement idea Jorgen Grahn <grahn+nntp@snipabacken.se> - 2020-01-24 17:26 +0000
                Re: two's complement idea Bart <bc@freeuk.com> - 2020-01-24 17:35 +0000
                Re: two's complement idea Paavo Helde <myfirstname@osa.pri.ee> - 2020-01-24 22:27 +0200
                Re: two's complement idea James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-01-24 23:21 -0500
                Re: two's complement idea Ian Collins <ian-news@hotmail.com> - 2020-01-25 11:06 +1300
                Re: two's complement idea Jorgen Grahn <grahn+nntp@snipabacken.se> - 2020-01-24 22:12 +0000
                Re: two's complement idea James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-01-24 23:24 -0500
                Re: two's complement idea Jorgen Grahn <grahn+nntp@snipabacken.se> - 2020-01-25 09:04 +0000
                Re: two's complement idea Öö Tiib <ootiib@hot.ee> - 2020-01-25 04:15 -0800
                Re: two's complement idea David Brown <david.brown@hesbynett.no> - 2020-01-25 19:55 +0100
                Re: two's complement idea David Brown <david.brown@hesbynett.no> - 2020-01-25 00:05 +0100
                Re: two's complement idea Bart <bc@freeuk.com> - 2020-01-25 01:19 +0000
                Re: two's complement idea Ian Collins <ian-news@hotmail.com> - 2020-01-25 19:50 +1300
                Re: two's complement idea Bart <bc@freeuk.com> - 2020-01-25 11:57 +0000
                Re: two's complement idea Chris Vine <chris@cvine--nospam--.freeserve.co.uk> - 2020-01-25 13:42 +0000
                Re: two's complement idea Bart <bc@freeuk.com> - 2020-01-25 14:58 +0000
                Re: two's complement idea Ian Collins <ian-news@hotmail.com> - 2020-01-26 07:58 +1300
                Re: two's complement idea David Brown <david.brown@hesbynett.no> - 2020-01-25 20:34 +0100
                Re: two's complement idea Öö Tiib <ootiib@hot.ee> - 2020-01-25 12:41 -0800
                Re: two's complement idea Paavo Helde <myfirstname@osa.pri.ee> - 2020-01-26 16:08 +0200
                Re: two's complement idea Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-01-27 02:20 -0800
                Re: two's complement idea Paavo Helde <myfirstname@osa.pri.ee> - 2020-01-27 15:03 +0200
                Re: two's complement idea Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-02-15 06:44 -0800
                Re: two's complement idea Paavo Helde <myfirstname@osa.pri.ee> - 2020-03-06 10:18 +0200
                Re: two's complement idea Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-04-02 07:05 -0700
                Re: two's complement idea Paavo Helde <myfirstname@osa.pri.ee> - 2020-04-02 20:03 +0300
                Re: two's complement idea Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-04-04 12:37 -0700
                Re: two's complement idea Ian Collins <ian-news@hotmail.com> - 2020-01-26 07:45 +1300
                Re: two's complement idea Bart <bc@freeuk.com> - 2020-01-25 19:56 +0000
                Re: two's complement idea Ian Collins <ian-news@hotmail.com> - 2020-01-26 09:49 +1300
                Re: two's complement idea Bart <bc@freeuk.com> - 2020-01-25 21:33 +0000
                Re: two's complement idea Ian Collins <ian-news@hotmail.com> - 2020-01-26 11:00 +1300
                Re: two's complement idea Bart <bc@freeuk.com> - 2020-01-25 22:23 +0000
                Re: two's complement idea Ian Collins <ian-news@hotmail.com> - 2020-01-26 11:46 +1300
                Re: two's complement idea Paavo Helde <myfirstname@osa.pri.ee> - 2020-01-26 10:55 +0200
                Re: two's complement idea Öö Tiib <ootiib@hot.ee> - 2020-01-26 03:47 -0800
                Re: two's complement idea Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-01-27 01:28 -0800
                Re: two's complement idea Jorgen Grahn <grahn+nntp@snipabacken.se> - 2020-01-25 22:22 +0000
                Re: two's complement idea James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-01-25 18:24 -0500
                Re: two's complement idea David Brown <david.brown@hesbynett.no> - 2020-01-26 12:54 +0100
                Re: two's complement idea Bart <bc@freeuk.com> - 2020-01-26 12:44 +0000
                Re: two's complement idea David Brown <david.brown@hesbynett.no> - 2020-01-26 14:58 +0100
                Re: two's complement idea Bart <bc@freeuk.com> - 2020-01-26 14:53 +0000
                Re: two's complement idea David Brown <david.brown@hesbynett.no> - 2020-01-26 19:10 +0100
                Re: two's complement idea Robert Wessel <robertwessel2@yahoo.com> - 2020-01-26 13:20 -0600
                Re: two's complement idea Bart <bc@freeuk.com> - 2020-01-26 20:51 +0000
                Re: two's complement idea Robert Wessel <robertwessel2@yahoo.com> - 2020-01-26 21:02 -0600
                Re: two's complement idea Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-01-26 19:06 -0800
                Re: two's complement idea Bart <bc@freeuk.com> - 2020-01-27 18:50 +0000
                Re: two's complement idea Robert Wessel <robertwessel2@yahoo.com> - 2020-01-27 14:18 -0600
                Re: two's complement idea David Brown <david.brown@hesbynett.no> - 2020-01-27 22:13 +0100
                Re: two's complement idea Bart <bc@freeuk.com> - 2020-01-27 21:38 +0000
                Re: two's complement idea Robert Wessel <robertwessel2@yahoo.com> - 2020-01-27 19:37 -0600
                Re: two's complement idea Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-01-27 19:15 -0800
                Re: two's complement idea "Fred. Zwarts" <F.Zwarts@KVI.nl> - 2020-01-28 11:45 +0100
                Re: two's complement idea Ian Collins <ian-news@hotmail.com> - 2020-01-27 16:31 +1300
                Re: two's complement idea Manfred <noname@add.invalid> - 2020-01-26 18:50 +0100
                Re: two's complement idea Jorgen Grahn <grahn+nntp@snipabacken.se> - 2020-01-26 18:57 +0000
                Re: two's complement idea David Brown <david.brown@hesbynett.no> - 2020-01-26 20:46 +0100
                Re: two's complement idea Robert Wessel <robertwessel2@yahoo.com> - 2020-01-26 13:14 -0600
                Re: two's complement idea David Brown <david.brown@hesbynett.no> - 2020-01-26 22:15 +0100
                Re: two's complement idea Robert Wessel <robertwessel2@yahoo.com> - 2020-01-27 21:06 -0600
                Re: two's complement idea David Brown <david.brown@hesbynett.no> - 2020-01-28 13:08 +0100
                Re: two's complement idea Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-01-27 01:50 -0800
                Re: two's complement idea Ian Collins <ian-news@hotmail.com> - 2020-01-27 08:21 +1300
                Re: two's complement idea David Brown <david.brown@hesbynett.no> - 2020-01-25 20:14 +0100
                Re: two's complement idea David Brown <david.brown@hesbynett.no> - 2020-01-25 20:12 +0100
                Re: two's complement idea Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-01-27 07:48 -0800
                Re: two's complement idea Bonita Montero <Bonita.Montero@gmail.com> - 2020-02-18 18:46 +0100

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