Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
Groups > comp.lang.c > #156868
| From | Anton Shepelev <anton.txt@gmail.com> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: Effective uses of c `goto' statement |
| Date | 2020-12-02 20:18 +0300 |
| Organization | A noiseless patient Spider |
| Message-ID | <20201202201819.a05fb6f16d51c686ba26d1f0@gmail.com> (permalink) |
| References | <87czzszjhs.fsf@fedora.osfans.org> |
kevin shell:
> Hello C hackers/masters. :-)
Not me...
> A lot of C textbooks say not to use `goto' statement, but
> the fact is I find lots of Unix/Linux C code often use
> `goto' statement.
Of course, and Linux Torvalds himself explains it:
https://web.archive.org/web/20171017142915/http://koblents.com/Ches/Links/Month-Mar-2013/20-Using-Goto-in-Linux-Kernel-Code/
> My question is how to effectively use `goto' statement
> with C code, how to use `goto' to jump forward and jump
> back, how to avoid multiple `goto' statements with both
> jump forward and jump backward in the same function from
> messing up?
I never jump upwards and use forward `goto' statements
1. to handle stack-like resource deallocation,
2. to handle errors, and
3. as a general means of early bail-out.
They are very efficient in reducing indentation, which is
one of the Seven pillars of readable code:
https://web.archive.org/web/20160517045517/http://www.perforce.com/resources/seven-pillars-pretty-code
I always strive to reduce the average level of indentation.
My rule is to test for the shortest branch and bail out,
e.g. instead of
if( a )
{ /* some */
/* lagrge */
/* piece */
/* of */
/* code */
}
else
{ report_error(); }
I write:
if( !a )
{ report_error();
goto Done;
}
/* some */
/* lagrge */
/* piece */
/* of */
/* code */
Done:
When inside a loop, use `continue', e.g. instead of
for( i = 0; i < n; i += 1 )
{ if( a )
{ /* large */
/* block */
/* A */
if( b )
{ /* large */
/* block */
/* B */
}
else
{ error1(); }
}
else
{ error2(); }
}
write:
for( i = 0; i < n; i += 1 )
{ if( !a )
{ error2();
continue;
}
/* large */
/* block */
/* A */
if( !b )
{ error2();
continue;
}
/* large */
/* block */
/* B */
}
-- the idea is to flatten long linearly structured
conditions, so that adding another condition (large block C
and error3()) shall not increase indentation.
For handling errors, see my comments to Ned Batchelder's
articles about exceptions:
https://nedbatchelder.com/text/exceptions-vs-status.html#comment_15239
--
() ascii ribbon campaign -- against html e-mail
/\ http://preview.tinyurl.com/qcy6mjc [archived]
Back to comp.lang.c | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
Effective uses of c `goto' statement kevin shell <kevin@fedora.osfans.org> - 2020-12-02 16:42 +0800
Re: Effective uses of c `goto' statement Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-12-02 01:07 -0800
Re: Effective uses of c `goto' statement Anton Shepelev <anton.txt@gmail.com> - 2020-12-02 20:18 +0300
Re: Effective uses of c `goto' statement Anton Shepelev <anton.txt@gmail.com> - 2020-12-02 20:56 +0300
Re: Effective uses of c `goto' statement David Brown <david.brown@hesbynett.no> - 2020-12-02 19:30 +0100
Re: Effective uses of c `goto' statement Kaz Kylheku <563-365-8930@kylheku.com> - 2020-12-02 19:35 +0000
Re: Effective uses of c `goto' statement David Brown <david.brown@hesbynett.no> - 2020-12-02 21:05 +0100
Re: Effective uses of c `goto' statement Vir Campestris <vir.campestris@invalid.invalid> - 2020-12-02 18:07 +0000
Re: Effective uses of c `goto' statement David Brown <david.brown@hesbynett.no> - 2020-12-02 19:33 +0100
Re: Effective uses of c `goto' statement Siri Cruise <chine.bleu@yahoo.com> - 2020-12-02 10:22 -0800
Re: Effective uses of c `goto' statement Kaz Kylheku <563-365-8930@kylheku.com> - 2020-12-02 20:18 +0000
Re: Effective uses of c `goto' statement David Brown <david.brown@hesbynett.no> - 2020-12-02 23:16 +0100
Re: Effective uses of c `goto' statement Kaz Kylheku <563-365-8930@kylheku.com> - 2020-12-03 01:31 +0000
Re: Effective uses of c `goto' statement David Brown <david.brown@hesbynett.no> - 2020-12-03 08:39 +0100
Re: Effective uses of c `goto' statement Siri Cruise <chine.bleu@yahoo.com> - 2020-12-02 23:48 -0800
Re: Effective uses of c `goto' statement Kaz Kylheku <563-365-8930@kylheku.com> - 2020-12-03 17:49 +0000
Re: Effective uses of c `goto' statement Bonita Montero <Bonita.Montero@gmail.com> - 2020-12-03 17:09 +0100
Re: Effective uses of c `goto' statement Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-12-05 08:28 -0800
Re: Effective uses of c `goto' statement Richard Damon <Richard@Damon-Family.org> - 2020-12-05 12:41 -0500
Re: Effective uses of c `goto' statement Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-12-06 05:03 -0800
Re: Effective uses of c `goto' statement Richard Damon <Richard@Damon-Family.org> - 2020-12-06 08:51 -0500
Re: Effective uses of c `goto' statement Richard Damon <Richard@Damon-Family.org> - 2020-12-06 08:56 -0500
Re: Effective uses of c `goto' statement Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-12-06 18:43 -0800
Re: Effective uses of c `goto' statement Öö Tiib <ootiib@hot.ee> - 2020-12-06 05:58 -0800
Re: Effective uses of c `goto' statement Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-12-06 16:54 -0800
Re: Effective uses of c `goto' statement Siri Cruise <chine.bleu@yahoo.com> - 2020-12-05 10:01 -0800
Re: Effective uses of c `goto' statement Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-12-06 04:55 -0800
Re: Effective uses of c `goto' statement Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-12-03 21:20 -0800
Re: Effective uses of c `goto' statement Siri Cruise <chine.bleu@yahoo.com> - 2020-12-03 21:50 -0800
Re: Effective uses of c `goto' statement Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-12-03 23:06 -0800
Re: Effective uses of c `goto' statement Siri Cruise <chine.bleu@yahoo.com> - 2020-12-04 00:27 -0800
Re: Effective uses of c `goto' statement foo <opaquefoo@gmail.com> - 2020-12-02 11:03 -0800
Re: Effective uses of c `goto' statement David Brown <david.brown@hesbynett.no> - 2020-12-02 21:02 +0100
Re: Effective uses of c `goto' statement Öö Tiib <ootiib@hot.ee> - 2020-12-05 03:04 -0800
Re: Effective uses of c `goto' statement Öö Tiib <ootiib@hot.ee> - 2020-12-05 03:36 -0800
Good thing this isn't a Python group (Was: Effective uses of c `goto' statement) gazelle@shell.xmission.com (Kenny McCormack) - 2020-12-05 11:45 +0000
Re: Good thing this isn't a Python group (Was: Effective uses of c `goto' statement) David Brown <david.brown@hesbynett.no> - 2020-12-05 14:38 +0100
Re: Good thing this isn't a Python group (Was: Effective uses of c `goto' statement) Jorgen Grahn <grahn+nntp@snipabacken.se> - 2020-12-06 11:00 +0000
Re: Good thing this isn't a Python group (Was: Effective uses of c `goto' statement) gazelle@shell.xmission.com (Kenny McCormack) - 2020-12-06 12:33 +0000
Re: Good thing this isn't a Python group Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-12-06 14:09 -0800
Re: Good thing this isn't a Python group Jorgen Grahn <grahn+nntp@snipabacken.se> - 2020-12-08 21:01 +0000
Re: Effective uses of c `goto' statement David Brown <david.brown@hesbynett.no> - 2020-12-05 14:37 +0100
Re: Effective uses of c `goto' statement Kaz Kylheku <563-365-8930@kylheku.com> - 2020-12-02 20:07 +0000
Re: Effective uses of c `goto' statement Bonita Montero <Bonita.Montero@gmail.com> - 2020-12-03 17:10 +0100
Re: Effective uses of c `goto' statement "jfbod...@gmail.com" <jfbode1029@gmail.com> - 2020-12-03 15:40 -0800
Re: Effective uses of c `goto' statement Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-12-03 16:14 -0800
Re: Effective uses of c `goto' statement kevin shell <kevin@fedora.osfans.org> - 2020-12-04 16:29 +0800
Re: Effective uses of c `goto' statement "jfbod...@gmail.com" <jfbode1029@gmail.com> - 2020-12-04 07:09 -0800
Re: Effective uses of c `goto' statement "james...@alumni.caltech.edu" <jameskuyper@alumni.caltech.edu> - 2020-12-04 10:14 -0800
Re: Effective uses of c `goto' statement Bart <bc@freeuk.com> - 2020-12-04 11:19 +0000
Re: Effective uses of c `goto' statement Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-12-04 04:35 -0800
Re: Effective uses of c `goto' statement Bart <bc@freeuk.com> - 2020-12-04 13:50 +0000
Re: Effective uses of c `goto' statement Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-12-04 10:49 -0800
Re: Effective uses of c `goto' statement Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-12-04 13:09 +0000
Re: Effective uses of c `goto' statement Bart <bc@freeuk.com> - 2020-12-04 14:03 +0000
Re: Effective uses of c `goto' statement Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-12-03 23:02 -0800
Re: Effective uses of c `goto' statement Bonita Montero <Bonita.Montero@gmail.com> - 2020-12-04 19:38 +0100
Re: Effective uses of c `goto' statement Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-12-05 01:29 -0800
Re: Effective uses of c `goto' statement kegs@provalid.com (Kent Dickey) - 2020-12-09 00:23 -0600
Re: Effective uses of c `goto' statement Bart <bc@freeuk.com> - 2020-12-09 12:39 +0000
Re: Effective uses of c `goto' statement Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-12-10 10:45 -0800
Re: Effective uses of c `goto' statement Bonita Montero <Bonita.Montero@gmail.com> - 2020-12-04 19:35 +0100
Re: Effective uses of c `goto' statement Richard Damon <Richard@Damon-Family.org> - 2020-12-04 19:49 -0500
Re: Effective uses of c `goto' statement Richard Damon <Richard@Damon-Family.org> - 2020-12-04 20:52 -0500
Re: Effective uses of c `goto' statement Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-12-05 02:19 +0000
Re: Effective uses of c `goto' statement Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-12-05 01:43 -0800
Re: Effective uses of c `goto' statement "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2020-12-05 02:00 -0800
Re: Effective uses of c `goto' statement "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2020-12-05 02:01 -0800
Re: Effective uses of c `goto' statement Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-12-05 22:45 +0000
Re: Effective uses of c `goto' statement "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2020-12-11 19:33 -0800
Re: Effective uses of c `goto' statement Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-12-12 21:12 +0000
Re: Effective uses of c `goto' statement Bart <bc@freeuk.com> - 2020-12-05 12:49 +0000
Re: Effective uses of c `goto' statement Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-12-05 22:42 +0000
Re: Effective uses of c `goto' statement Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-12-06 05:46 -0800
Re: Effective uses of c `goto' statement Bart <bc@freeuk.com> - 2020-12-06 14:16 +0000
Re: Effective uses of c `goto' statement Öö Tiib <ootiib@hot.ee> - 2020-12-06 06:54 -0800
Re: Effective uses of c `goto' statement Bart <bc@freeuk.com> - 2020-12-06 16:19 +0000
Re: Effective uses of c `goto' statement Öö Tiib <ootiib@hot.ee> - 2020-12-06 15:34 -0800
Re: Effective uses of c `goto' statement Bart <bc@freeuk.com> - 2020-12-06 23:56 +0000
Re: Effective uses of c `goto' statement David Brown <david.brown@hesbynett.no> - 2020-12-07 11:11 +0100
Re: Effective uses of c `goto' statement Bart <bc@freeuk.com> - 2020-12-07 11:41 +0000
Re: Effective uses of c `goto' statement David Brown <david.brown@hesbynett.no> - 2020-12-07 15:35 +0100
Re: Effective uses of c `goto' statement Bart <bc@freeuk.com> - 2020-12-07 15:48 +0000
Re: Effective uses of c `goto' statement Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-12-07 11:46 -0800
Re: Effective uses of c `goto' statement Bart <bc@freeuk.com> - 2020-12-07 20:01 +0000
Re: Effective uses of c `goto' statement Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-12-07 13:03 -0800
Re: Effective uses of c `goto' statement David Brown <david.brown@hesbynett.no> - 2020-12-07 11:01 +0100
Re: Effective uses of c `goto' statement Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-12-07 03:35 -0800
Re: Effective uses of c `goto' statement Richard Damon <Richard@Damon-Family.org> - 2020-12-07 07:33 -0500
Re: Effective uses of c `goto' statement gazelle@shell.xmission.com (Kenny McCormack) - 2020-12-07 13:11 +0000
Re: Effective uses of c `goto' statement Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-12-07 05:24 -0800
Re: Effective uses of c `goto' statement Richard Damon <Richard@Damon-Family.org> - 2020-12-07 08:58 -0500
Re: Effective uses of c `goto' statement David Brown <david.brown@hesbynett.no> - 2020-12-07 15:48 +0100
Re: Effective uses of c `goto' statement David Brown <david.brown@hesbynett.no> - 2020-12-07 15:45 +0100
Re: Effective uses of c `goto' statement Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-12-07 07:29 -0800
Re: Effective uses of c `goto' statement Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-12-07 22:34 +0000
Re: Effective uses of c `goto' statement David Brown <david.brown@hesbynett.no> - 2020-12-07 15:38 +0100
Re: Effective uses of c `goto' statement kegs@provalid.com (Kent Dickey) - 2020-12-10 15:45 -0600
Re: Effective uses of c `goto' statement Vir Campestris <vir.campestris@invalid.invalid> - 2020-12-07 21:43 +0000
Re: Effective uses of c `goto' statement Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-12-07 23:02 +0000
Re: Effective uses of c `goto' statement Vir Campestris <vir.campestris@invalid.invalid> - 2020-12-10 21:15 +0000
Re: Effective uses of c `goto' statement Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-12-10 22:48 +0000
Re: Effective uses of c `goto' statement Vir Campestris <vir.campestris@invalid.invalid> - 2020-12-11 20:59 +0000
Re: Effective uses of c `goto' statement Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-12-11 14:07 -0800
Re: Effective uses of c `goto' statement Bonita Montero <Bonita.Montero@gmail.com> - 2020-12-05 08:55 +0100
Re: Effective uses of c `goto' statement Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-12-05 02:04 -0800
Re: Effective uses of c `goto' statement Vir Campestris <vir.campestris@invalid.invalid> - 2020-12-07 21:37 +0000
Re: Effective uses of c `goto' statement James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-12-07 17:03 -0500
Re: Effective uses of c `goto' statement David Brown <david.brown@hesbynett.no> - 2020-12-07 23:17 +0100
Re: Effective uses of c `goto' statement Kaz Kylheku <563-365-8930@kylheku.com> - 2020-12-07 22:19 +0000
Re: Effective uses of c `goto' statement Vir Campestris <vir.campestris@invalid.invalid> - 2020-12-10 21:13 +0000
Re: Effective uses of c `goto' statement kegs@provalid.com (Kent Dickey) - 2020-12-10 15:30 -0600
Re: Effective uses of c `goto' statement "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2020-12-05 13:01 -0500
Re: Effective uses of c `goto' statement luser droog <luser.droog@gmail.com> - 2020-12-11 19:27 -0800
csiph-web