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Groups > comp.lang.c > #149895

Re: Coding style for small if statements

From Ben Bacarisse <ben.usenet@bsb.me.uk>
Newsgroups comp.lang.c
Subject Re: Coding style for small if statements
Date 2020-02-09 21:29 +0000
Organization A noiseless patient Spider
Message-ID <87a75rlaaa.fsf@bsb.me.uk> (permalink)
References (7 earlier) <r1mn3m$dtk$1@dont-email.me> <875zggms21.fsf@bsb.me.uk> <r1osb3$4a5$1@dont-email.me> <87zhdrlqns.fsf@bsb.me.uk> <Bq_%F.306370$5X1.227452@fx06.am4>

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Bart <bc@freeuk.com> writes:

> On 09/02/2020 15:35, Ben Bacarisse wrote:
>> David Brown <david.brown@hesbynett.no> writes:
>
>>>      if ((err = SSLHashSHA1.update(&hashCtx, &serverRandom)) != 0)
>>>          goto fail;
>>>      if ((err = SSLHashSHA1.update(&hashCtx, &signedParams)) != 0)
>>>          goto fail;
>>>          goto fail;
>>>      if ((err = SSLHashSHA1.final(&hashCtx, &hashOut)) != 0)
>>>          goto fail;
<cut>
>> This is a classic example of why goto is considered harmful.  The bug
>> comes from the fact that the fail label (presumably) just returns err.
>> Every place where you have
>>
>>    label:
>>        <code>;
>>
>> in a C function you must check (and test) every place from which you can
>> get here.  That's why I hate gotos so much and why I am cautious about
>> breaks.  The pre-conditions for "<code>" are hard to determine.
>
> I thought compilers like the ones David uses would tell you that the
> statement after the unconditional goto was unreachable.

Yes, but since he already mentioned that better tools could have spotted
the error I did not think it needed to be mentioned again.

But in the part you appeared to be replying to I was making a general
point about labels and why I dislike gotos: at the label you have to
assemble a complex picture of the program's state at all the points you
could have come to it from.

-- 
Ben.

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Thread

Coding style for small if statements Anton Shepelev <anton.txt@gmail.com> - 2020-01-31 23:46 +0300
  Re: Coding style for small if statements Anton Shepelev <anton.txt@gmail.com> - 2020-01-31 23:54 +0300
    Re: Coding style for small if statements Les Cargill <lcargill99@comcast.com> - 2020-01-31 19:13 -0600
    Re: Coding style for small if statements Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-02-22 07:52 -0800
  Re: Coding style for small if statements Anton Shepelev <anton.txt@gmail.com> - 2020-02-01 00:06 +0300
    Re: Coding style for small if statements mathog <dmathog@gmail.com> - 2020-02-28 10:20 -0800
  Re: Coding style for small if statements Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2020-01-31 16:28 -0500
  Re: Coding style for small if statements donalhambra@gmail.com - 2020-02-01 04:55 -0800
    Re: Coding style for small if statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-02-01 17:16 +0000
      Re: Coding style for small if statements luser droog <luser.droog@gmail.com> - 2020-02-02 11:03 -0800
        Re: Coding style for small if statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-02-03 02:20 +0000
      Re: Coding style for small if statements Bonita Montero <Bonita.Montero@gmail.com> - 2020-02-03 05:17 +0100
        Re: Coding style for small if statements chad <cdalten@gmail.com> - 2020-02-03 04:07 -0800
          Re: Coding style for small if statements luser droog <luser.droog@gmail.com> - 2020-02-03 12:59 -0800
            Re: Coding style for small if statements chad <cdalten@gmail.com> - 2020-02-03 20:54 -0800
  Re: Coding style for small if statements nobody@example.org (Scott) - 2020-02-01 16:44 +0000
  Re: Coding style for small if statements already5chosen@yahoo.com - 2020-02-02 04:40 -0800
  Re: Coding style for small if statements David Brown <david.brown@hesbynett.no> - 2020-02-02 15:47 +0100
  Re: Coding style for small if statements Jorgen Grahn <grahn+nntp@snipabacken.se> - 2020-02-03 23:56 +0000
    Re: Coding style for small if statements Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-02-16 05:34 -0800
      Re: Coding style for small if statements Jorgen Grahn <grahn+nntp@snipabacken.se> - 2020-02-16 16:17 +0000
        Re: Coding style for small if statements Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-02-22 08:28 -0800
  Re: Coding style for small if statements skybuck2000@hotmail.com - 2020-02-03 21:52 -0800
    Re: Coding style for small if statements skybuck2000@hotmail.com - 2020-02-03 22:07 -0800
      Re: Coding style for small if statements skybuck2000@hotmail.com - 2020-02-03 22:22 -0800
        Re: Coding style for small if statements skybuck2000@hotmail.com - 2020-02-03 22:25 -0800
        Re: Coding style for small if statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-02-05 02:35 +0000
          Re: Coding style for small if statements James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-02-04 20:20 -0800
            Re: Coding style for small if statements James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-02-05 01:04 -0500
            Re: Coding style for small if statements James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-02-05 01:05 -0500
  Re: Coding style for small if statements John Bode <jfbode1029@gmail.com> - 2020-02-05 12:50 -0800
    Re: Coding style for small if statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-02-05 23:36 +0000
      Re: Coding style for small if statements John Bode <jfbode1029@gmail.com> - 2020-02-06 15:01 -0800
        Re: Coding style for small if statements Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-02-06 15:43 -0800
          Re: Coding style for small if statements David Brown <david.brown@hesbynett.no> - 2020-02-07 11:02 +0100
            Re: Coding style for small if statements scott@slp53.sl.home (Scott Lurndal) - 2020-02-07 15:24 +0000
              Re: Coding style for small if statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-02-07 23:03 +0000
                Re: Coding style for small if statements scott@slp53.sl.home (Scott Lurndal) - 2020-02-07 23:59 +0000
                Re: Coding style for small if statements Bart <bc@freeuk.com> - 2020-02-08 00:16 +0000
                Re: Coding style for small if statements scott@slp53.sl.home (Scott Lurndal) - 2020-02-08 02:26 +0000
          Re: Coding style for small if statements Les Cargill <lcargill99@comcast.com> - 2020-02-08 17:07 -0600
            Re: Coding style for small if statements Bart <bc@freeuk.com> - 2020-02-08 23:17 +0000
              Re: Coding style for small if statements Les Cargill <lcargill99@comcast.com> - 2020-02-08 18:32 -0600
                Re: Coding style for small if statements Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-02-09 09:32 -0800
            Re: Coding style for small if statements Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-02-16 07:10 -0800
        Re: Coding style for small if statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-02-07 01:26 +0000
          Re: Coding style for small if statements David Brown <david.brown@hesbynett.no> - 2020-02-07 11:30 +0100
            Re: Coding style for small if statements chad <cdalten@gmail.com> - 2020-02-07 05:36 -0800
            Re: Coding style for small if statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-02-07 23:36 +0000
              Re: Coding style for small if statements David Brown <david.brown@hesbynett.no> - 2020-02-08 17:20 +0100
                Re: Coding style for small if statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-02-09 02:07 +0000
                Re: Coding style for small if statements David Brown <david.brown@hesbynett.no> - 2020-02-09 13:01 +0100
                Re: Coding style for small if statements Bart <bc@freeuk.com> - 2020-02-09 13:26 +0000
                Re: Coding style for small if statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-02-09 15:53 +0000
                Re: Coding style for small if statements David Brown <david.brown@hesbynett.no> - 2020-02-09 17:03 +0100
                Re: Coding style for small if statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-02-09 15:35 +0000
                Re: Coding style for small if statements Manfred <noname@add.invalid> - 2020-02-09 18:07 +0100
                Re: Coding style for small if statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-02-09 21:17 +0000
                Pre- and post- conditions (was Re: Coding style for small if statements) Jorgen Grahn <grahn+nntp@snipabacken.se> - 2020-02-11 07:19 +0000
                Re: Pre- and post- conditions (was Re: Coding style for small if statements) Öö Tiib <ootiib@hot.ee> - 2020-02-10 23:40 -0800
                Re: Pre- and post- conditions (was Re: Coding style for small if statements) Jorgen Grahn <grahn+nntp@snipabacken.se> - 2020-02-12 12:24 +0000
                Re: Pre- and post- conditions (was Re: Coding style for small if statements) Bart <bc@freeuk.com> - 2020-02-11 11:30 +0000
                Re: Pre- and post- conditions (was Re: Coding style for small if statements) Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2020-02-11 09:41 -0700
                Re: Pre- and post- conditions (was Re: Coding style for small if statements) James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-02-12 08:12 -0500
                Re: Pre- and post- conditions (was Re: Coding style for small if statements) Jorgen Grahn <grahn+nntp@snipabacken.se> - 2020-02-14 21:18 +0000
                Re: Pre- and post- conditions (was Re: Coding style for small if statements) Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-02-22 00:01 -0800
                Re: Pre- and post- conditions (was Re: Coding style for small if statements) James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-02-22 05:22 -0800
                Re: Pre- and post- conditions (was Re: Coding style for small if statements) Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-04-02 07:57 -0700
                Re: Pre- and post- conditions (was Re: Coding style for small if statements) James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-04-02 08:28 -0700
                Re: Pre- and post- conditions (was Re: Coding style for small if statements) jadill33@gmail.com - 2020-02-12 07:56 -0800
                Re: Pre- and post- conditions (was Re: Coding style for small if statements) chad <cdalten@gmail.com> - 2020-02-12 08:57 -0800
                Re: Pre- and post- conditions (was Re: Coding style for small if statements) Jorgen Grahn <grahn+nntp@snipabacken.se> - 2020-02-14 21:31 +0000
                Re: Pre- and post- conditions (was Re: Coding style for small if statements) jadill33@gmail.com - 2020-02-14 14:10 -0800
                Re: Pre- and post- conditions (was Re: Coding style for small if statements) Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-02-15 03:06 +0000
                Re: Coding style for small if statements David Brown <david.brown@hesbynett.no> - 2020-02-09 19:45 +0100
                Re: Coding style for small if statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-02-09 21:50 +0000
                Re: Coding style for small if statements Bart <bc@freeuk.com> - 2020-02-09 22:51 +0000
                Re: Coding style for small if statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-02-10 01:39 +0000
                Re: Coding style for small if statements David Brown <david.brown@hesbynett.no> - 2020-02-10 09:55 +0100
                Re: Coding style for small if statements Bart <bc@freeuk.com> - 2020-02-10 11:07 +0000
                Re: Coding style for small if statements David Brown <david.brown@hesbynett.no> - 2020-02-10 12:48 +0100
                Re: Coding style for small if statements Bart <bc@freeuk.com> - 2020-02-10 13:13 +0000
                Re: Coding style for small if statements David Brown <david.brown@hesbynett.no> - 2020-02-10 15:15 +0100
                Re: Coding style for small if statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-02-10 15:46 +0000
                Re: Coding style for small if statements James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-02-09 18:18 -0800
                Re: Coding style for small if statements David Brown <david.brown@hesbynett.no> - 2020-02-10 09:12 +0100
                Re: Coding style for small if statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-02-10 14:51 +0000
                Re: Coding style for small if statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-02-10 16:19 +0000
                Re: Coding style for small if statements Bart <bc@freeuk.com> - 2020-02-09 21:00 +0000
                Re: Coding style for small if statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-02-09 21:29 +0000
                Re: Coding style for small if statements luser droog <luser.droog@gmail.com> - 2020-02-09 17:14 -0800
                Re: Coding style for small if statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-02-09 21:15 +0000
                Re: Coding style for small if statements James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-02-09 18:43 -0500
                Re: Coding style for small if statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-02-10 01:25 +0000
                Re: Coding style for small if statements Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-02-22 01:19 -0800
    Re: Coding style for small if statements Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-02-16 05:43 -0800
      Re: Coding style for small if statements Bart <bc@freeuk.com> - 2020-02-16 14:01 +0000
        Re: Coding style for small if statements Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-02-22 08:34 -0800
  Re: Coding style for small if statements Guillaume <message@bottle.org> - 2020-02-07 15:25 +0100
    Re: Coding style for small if statements Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-02-07 07:22 -0800
      Re: Coding style for small if statements Anton Shepelev <anton.txt@g{oogle}mail.com> - 2020-02-14 15:21 +0300
        Re: Coding style for small if statements Bart <bc@freeuk.com> - 2020-02-14 13:35 +0000
        Re: Coding style for small if statements Guillaume <message@bottle.org> - 2020-02-14 14:43 +0100
          Re: Coding style for small if statements David Brown <david.brown@hesbynett.no> - 2020-02-15 12:08 +0100
          Re: Coding style for small if statements Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-02-20 10:10 -0800
            Re: Coding style for small if statements David Brown <david.brown@hesbynett.no> - 2020-02-20 19:58 +0100
      Re: Coding style for small if statements Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-02-16 05:55 -0800
    Re: Coding style for small if statements scott@slp53.sl.home (Scott Lurndal) - 2020-02-07 15:26 +0000
      Re: Coding style for small if statements luser droog <luser.droog@gmail.com> - 2020-02-07 17:47 -0800
        Re: Coding style for small if statements jadill33@gmail.com - 2020-02-10 07:09 -0800
      Re: Coding style for small if statements Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-02-16 06:30 -0800
        Re: Coding style for small if statements David Brown <david.brown@hesbynett.no> - 2020-02-16 16:14 +0100
          Re: Coding style for small if statements Jorgen Grahn <grahn+nntp@snipabacken.se> - 2020-02-16 16:40 +0000
            Re: Coding style for small if statements David Brown <david.brown@hesbynett.no> - 2020-02-16 17:48 +0100
            Re: Coding style for small if statements Robert Wessel <robertwessel2@yahoo.com> - 2020-02-16 17:14 -0600
            Re: Coding style for small if statements Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-03-30 00:27 -0700
        Re: Coding style for small if statements Ike Naar <ike@sdf.lonestar.org> - 2020-02-16 18:39 +0000
          Re: Coding style for small if statements Jorgen Grahn <grahn+nntp@snipabacken.se> - 2020-02-16 20:37 +0000
            Re: Coding style for small if statements David Brown <david.brown@hesbynett.no> - 2020-02-17 09:09 +0100
              Re: Coding style for small if statements Öö Tiib <ootiib@hot.ee> - 2020-02-17 05:32 -0800
              Re: Coding style for small if statements scott@slp53.sl.home (Scott Lurndal) - 2020-02-17 18:07 +0000
              Re: Coding style for small if statements Jorgen Grahn <grahn+nntp@snipabacken.se> - 2020-02-17 23:48 +0000
              Re: Coding style for small if statements Richard Damon <Richard@Damon-Family.org> - 2020-02-17 20:40 -0500
          Re: Coding style for small if statements Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-02-23 10:14 -0800
            Re: Coding style for small if statements Ike Naar <ike@iceland.freeshell.org> - 2020-02-23 20:16 +0000
              Re: Coding style for small if statements Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-03-29 18:56 -0700
                Re: Coding style for small if statements Ike Naar <ike@sdf.lonestar.org> - 2020-03-30 06:07 +0000
                Re: Coding style for small if statements Jorgen Grahn <grahn+nntp@snipabacken.se> - 2020-03-30 06:45 +0000
                Re: Coding style for small if statements David Brown <david.brown@hesbynett.no> - 2020-03-30 10:50 +0200
                Re: Coding style for small if statements gazelle@shell.xmission.com (Kenny McCormack) - 2020-03-30 13:04 +0000
                Re: Coding style for small if statements Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-03-30 06:17 -0700
                Re: Coding style for small if statements Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-04-04 14:09 -0700
    Re: Coding style for small if statements Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-02-18 02:09 -0800
  Re: Coding style for small if statements Jens Stuckelberger <Jens_Stuckelberger@nowhere.net> - 2020-02-10 01:47 +0000
  Re: Coding style for small if statements Bonita Montero <Bonita.Montero@gmail.com> - 2020-02-12 17:54 +0100
  Re: Coding style for small if statements Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-02-20 07:18 -0800
  Re: Coding style for small if statements fir <profesor.fir@gmail.com> - 2020-02-29 03:30 -0800

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