Re: Updating pointer with result of sprintf

From	Ben Bacarisse <ben.usenet@bsb.me.uk>
Newsgroups	comp.lang.c
Subject	Re: Updating pointer with result of sprintf
Date	2017-11-28 14:35 +0000
Organization	A noiseless patient Spider
Message-ID	<87o9nmtqsn.fsf@bsb.me.uk> (permalink)
References	<ovjd76$sbt$1@dont-email.me> <xfeTB.51669$514.20740@fx43.iad>

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scott@slp53.sl.home (Scott Lurndal) writes:

> Noob <root@127.0.0.1> writes:
>>Hello,
>>
>>Consider the following code:
>>
>>  unsigned char src[32]; /* initialized somewhere */
>>  char buf[65];
>>
>>  for (i = 0; i < sizeof src; ++i)
>>    buf += sprintf(buf, "%02x", src[i]);
>>
>
> You're better off using 'snprintf'.

Only if you assume the use-case is really quite different from the one
presented here.

> You can still
> increment a pointer using the result, but you'll
> want to check the result first, since it can return -1

Only on an encoding error, and I can't see how you can have one here.

> or can return a value greater than the buffer size if
> it truncated the output.

Again, not possible in this case.  Maybe the code is intended to be much
more complicated, in which case, sure go for snprintf, but it looks
like overkill at the moment.

<snip>
-- 
Ben.

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Thread

Updating pointer with result of sprintf Noob <root@127.0.0.1> - 2017-11-28 11:19 +0100
  Re: Updating pointer with result of sprintf bartc <bc@freeuk.com> - 2017-11-28 11:02 +0000
  Re: Updating pointer with result of sprintf jacobnavia <jacob@jacob.remcomp.fr> - 2017-11-28 12:09 +0100
    Re: Updating pointer with result of sprintf Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-11-28 11:23 +0000
    Re: Updating pointer with result of sprintf Keith Thompson <kst-u@mib.org> - 2017-11-28 08:58 -0800
  Re: Updating pointer with result of sprintf Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-11-28 11:10 +0000
    Re: Updating pointer with result of sprintf Spiros Bousbouras <spibou@gmail.com> - 2017-11-28 16:51 +0000
      Re: Updating pointer with result of sprintf Keith Thompson <kst-u@mib.org> - 2017-11-28 09:24 -0800
      Re: Updating pointer with result of sprintf Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-11-29 00:33 +0000
        Re: Updating pointer with result of sprintf Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-11-29 00:36 +0000
        Re: Updating pointer with result of sprintf Spiros Bousbouras <spibou@gmail.com> - 2017-11-29 19:04 +0000
  Re: Updating pointer with result of sprintf "Pascal J. Bourguignon" <pjb@informatimago.com> - 2017-11-28 12:47 +0100
    Re: Updating pointer with result of sprintf "Pascal J. Bourguignon" <pjb@informatimago.com> - 2017-11-28 12:49 +0100
  Re: Updating pointer with result of sprintf scott@slp53.sl.home (Scott Lurndal) - 2017-11-28 14:19 +0000
    Re: Updating pointer with result of sprintf gazelle@shell.xmission.com (Kenny McCormack) - 2017-11-28 14:27 +0000
    Re: Updating pointer with result of sprintf Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-11-28 14:35 +0000
  Re: Updating pointer with result of sprintf "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2017-11-28 06:31 -0800
    Re: Updating pointer with result of sprintf "Pascal J. Bourguignon" <pjb@informatimago.com> - 2017-11-28 15:51 +0100
      Re: Updating pointer with result of sprintf "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2017-11-28 07:23 -0800
        Re: Updating pointer with result of sprintf "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2017-11-28 08:16 -0800
          Re: Updating pointer with result of sprintf Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-11-28 16:32 +0000
            Re: Updating pointer with result of sprintf "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2017-11-28 08:57 -0800
            Re: Updating pointer with result of sprintf "Pascal J. Bourguignon" <pjb@informatimago.com> - 2017-11-29 00:47 +0100
          Re: Updating pointer with result of sprintf "Pascal J. Bourguignon" <pjb@informatimago.com> - 2017-11-29 00:45 +0100
      Re: Updating pointer with result of sprintf Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-11-28 16:22 +0000
        Re: Updating pointer with result of sprintf Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-11-28 16:25 +0000
        Re: Updating pointer with result of sprintf "Pascal J. Bourguignon" <pjb@informatimago.com> - 2017-11-29 00:48 +0100
  Re: Updating pointer with result of sprintf Noob <root@127.0.0.1> - 2017-11-29 10:07 +0100
    Re: Updating pointer with result of sprintf Barry Schwarz <schwarzb@dqel.com> - 2017-11-29 09:18 -0800

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