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Groups > comp.lang.c++ > #71635
| From | "Fred. Zwarts" <F.Zwarts@KVI.nl> |
|---|---|
| Newsgroups | comp.lang.c++ |
| Subject | Re: two's complement idea |
| Date | 2020-01-28 11:45 +0100 |
| Organization | Aioe.org NNTP Server |
| Message-ID | <r0p3bl$1dln$1@gioia.aioe.org> (permalink) |
| References | (11 earlier) <p3ks2f1vekfr0dckvguuvkrdr6lrpedrsl@4ax.com> <VhGXF.46342$BA5.20568@fx21.am4> <e1hu2f5p960nhg1spsvndon031nop7ldhr@4ax.com> <r0njph$86d$1@dont-email.me> <oLIXF.113152$%G5.81633@fx03.am4> |
Op 27.jan..2020 om 22:38 schreef Bart:
> On 27/01/2020 21:13, David Brown wrote:
>> On 27/01/2020 21:18, Robert Wessel wrote:
>>> On Mon, 27 Jan 2020 18:50:28 +0000, Bart <bc@freeuk.com> wrote:
>>>
>>>> On 27/01/2020 03:02, Robert Wessel wrote:
>>
>> <snip>
>>
>>>>> The label makes the association with the loop/switch
>>>>> of interest explicit. I view the issue as similar to that of
>>>>> significant white space for flow control (as in Python). A small
>>>>> advantage is that a meaningful label can provide documentation.
>>>>
>>>> Any label is going to be similar to a goto label (possibly, identical).
>>>>
>>>> That makes:
>>>>
>>>> break L;
>>>> ...
>>>> }
>>>> }
>>>> L: // or maybe the label is at the beginning
>>>>
>>>> not that different to:
>>>>
>>>> goto L;
>>>> ...
>>>> }
>>>> }
>>>> L:
>>>>
>>>> (Problem using a regular label is that you have to search the code to
>>>> see if you get there from goto, break, or both.)
>>>
>>>
>>> No the labels would be on the loop/switch statement. So:
>>>
>>> outerloop: for(...)
>>> {
>>> for(...)
>>> {
>>> ...
>>> if (...)
>>> break outerloop;
>>> ...
>>> }
>>> }
>>>
>>> That has two advantages - the label actually refers to the loop (or
>>> switch you're trying to do something with), and second, it's a natural
>>> extension to the language - labels are already (somewhat over
>>> simplified) a prefix on a statement. So valid targets for a
>>> break/continue are just enclosing statements of the right type with a
>>> label.
>>>
>>
>> That strikes me as a neat and clear way to break out of a nested loop.
>> In particular, it avoids the over-flexibility of goto - you can break
>> out of a loop, but you can't jump to arbitrary points in the code.
>> And a label makes it clear what you want to exit.
>>
>
> I just tried to implement that (in a C compiler), then I realised that
> the label I wanted wasn't actually at the start of the loop statement,
> but just past the end!
>
> That makes it harder (would have taken longer than the 20 minutes I'd
> set aside). And it raises one issue: if this label is also a legal goto
> label, then:
>
> outerloop:
> for(;;) { while(1) {
> goto outerloop;
> break outerloop;
> }}
> // endofouterloop:
>
> the statements will jump to completely different points. The break
> actually goes to an implicit statement after the loop.
>
> At this point, it seems to me the following would actually be clearer:
>
> for(;;) { while(1) {
> goto endofouterloop;
> }}
> endofouterloop:
>
> as it pinpoints exactly where the code will end up next. With loads of
> nested }s floating around, many nothing to do with the loops, the end of
> the desired loop is not always easy to find.
Maybe, but for a "continue outerloop;" a label at the beginning would be
more appropriate, or even better, inside the loop.
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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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