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Groups > comp.lang.c > #94459

Re: When parameters to printf are in memory

From Ben Bacarisse <ben.usenet@bsb.me.uk>
Newsgroups comp.lang.c
Subject Re: When parameters to printf are in memory
Date 2016-10-04 22:51 +0100
Organization A noiseless patient Spider
Message-ID <878tu3236k.fsf@bsb.me.uk> (permalink)
References (12 earlier) <nsvlm7$3r7$1@dont-email.me> <87fuoc33dx.fsf@bsb.me.uk> <nt0ua3$kcf$1@dont-email.me> <87eg3v2a03.fsf@bsb.me.uk> <nt10ia$sk9$1@dont-email.me>

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James Harris <james.harris.1@gmail.com> writes:

> On 04/10/2016 20:24, Ben Bacarisse wrote:
>> James Harris <james.harris.1@gmail.com> writes:
>>
>>> On 04/10/2016 09:49, Ben Bacarisse wrote:
>> <snip>
>>>> But there are very many other possible problems that come [down] to one
>>>> basic problem.  If the format has "%d" the corresponding argument must
>>>> be an int and not a union that might contain an int.
>>>
>>> So if I had
>>>
>>>   union any {
>>>     int16_t i16;
>>>     int i;
>>>     double d;
>>>   } u;
>>>
>>> I guess you are saying that the code to work with "%d" would have to
>>> refer to u.i instead of u?
>>
>> Yes, to follow the letter of the standard.
>
> That's not a major departure from what I had in mind because I
> expected it to follow the model of va_arg wherein the type has to be
> supplied. But if I use printf's format codes it could be awkward to
> pull the correctly adjusted size of type from the format string,
> e.g. the difference between d and ld.

Yes, that going to get fussy, but that's all.  If you supply a type that
either is the right one, or promotes to the right one, it must work.

<snip>
-- 
Ben.

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Thread

When parameters to printf are in memory James Harris <james.harris.1@gmail.com> - 2016-09-29 16:20 +0100
  Re: When parameters to printf are in memory James Harris <james.harris.1@gmail.com> - 2016-09-29 16:43 +0100
    Re: When parameters to printf are in memory Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-09-29 20:30 +0100
    Re: When parameters to printf are in memory James Harris <james.harris.1@gmail.com> - 2016-09-29 21:23 +0100
    Re: When parameters to printf are in memory BartC <bc@freeuk.com> - 2016-09-29 22:03 +0100
      Re: When parameters to printf are in memory James Harris <james.harris.1@gmail.com> - 2016-09-29 22:35 +0100
        Re: When parameters to printf are in memory BartC <bc@freeuk.com> - 2016-09-29 23:11 +0100
          Re: When parameters to printf are in memory James Harris <james.harris.1@gmail.com> - 2016-09-30 19:53 +0100
            Re: When parameters to printf are in memory Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-09-30 20:53 +0100
              Re: When parameters to printf are in memory James Harris <james.harris.1@gmail.com> - 2016-10-01 09:08 +0100
                Re: When parameters to printf are in memory BartC <bc@freeuk.com> - 2016-10-01 11:15 +0100
                Re: When parameters to printf are in memory James Harris <james.harris.1@gmail.com> - 2016-10-04 08:32 +0100
                Re: When parameters to printf are in memory Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-10-01 11:15 +0100
                Re: When parameters to printf are in memory James Harris <james.harris.1@gmail.com> - 2016-10-04 08:28 +0100
                Re: When parameters to printf are in memory Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-10-04 09:49 +0100
                Re: When parameters to printf are in memory BartC <bc@freeuk.com> - 2016-10-04 11:43 +0100
                Re: When parameters to printf are in memory Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-10-04 13:42 +0100
                Re: When parameters to printf are in memory BartC <bc@freeuk.com> - 2016-10-04 14:03 +0100
                Re: When parameters to printf are in memory Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-10-04 14:16 +0100
                Re: When parameters to printf are in memory James Harris <james.harris.1@gmail.com> - 2016-10-04 20:01 +0100
                Re: When parameters to printf are in memory Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-10-04 20:24 +0100
                Re: When parameters to printf are in memory James Harris <james.harris.1@gmail.com> - 2016-10-04 20:40 +0100
                Re: When parameters to printf are in memory Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-10-04 22:51 +0100
            Re: When parameters to printf are in memory "James R. Kuyper" <jameskuyper@verizon.net> - 2016-10-04 14:25 -0400
              Re: When parameters to printf are in memory James Harris <james.harris.1@gmail.com> - 2016-10-04 20:31 +0100
  Re: When parameters to printf are in memory BartC <bc@freeuk.com> - 2016-09-29 17:03 +0100
    Re: When parameters to printf are in memory gazelle@shell.xmission.com (Kenny McCormack) - 2016-09-30 12:20 +0000
      Re: When parameters to printf are in memory Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-09-30 05:55 -0700
      Re: When parameters to printf are in memory James Harris <james.harris.1@gmail.com> - 2016-09-30 20:06 +0100
        Re: When parameters to printf are in memory gazelle@shell.xmission.com (Kenny McCormack) - 2016-09-30 22:01 +0000
          Re: When parameters to printf are in memory James Harris <james.harris.1@gmail.com> - 2016-10-01 09:15 +0100
        Re: When parameters to printf are in memory Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-09-30 23:18 -0700
          Re: When parameters to printf are in memory James Harris <james.harris.1@gmail.com> - 2016-10-01 09:32 +0100
  Re: When parameters to printf are in memory jacobnavia <jacob@jacob.remcomp.fr> - 2016-09-29 18:35 +0200
    Re: When parameters to printf are in memory James Harris <james.harris.1@gmail.com> - 2016-09-29 19:55 +0100
      Re: When parameters to printf are in memory jacobnavia <jacob@jacob.remcomp.fr> - 2016-09-29 21:22 +0200
  Re: When parameters to printf are in memory Barry Schwarz <schwarzb@dqel.com> - 2016-09-29 11:20 -0700
    Re: When parameters to printf are in memory James Harris <james.harris.1@gmail.com> - 2016-09-29 20:08 +0100
  Re: When parameters to printf are in memory Lőrinczy Zsigmond <nospam@for.me> - 2016-10-02 20:15 +0200
    Re: When parameters to printf are in memory Lőrinczy Zsigmond <nospam@for.me> - 2016-10-02 20:19 +0200
      Re: When parameters to printf are in memory gazelle@shell.xmission.com (Kenny McCormack) - 2016-10-02 18:29 +0000
        Re: When parameters to printf are in memory Lőrinczy Zsigmond <nospam@for.me> - 2016-10-03 07:04 +0200
          Re: When parameters to printf are in memory James Harris <james.harris.1@gmail.com> - 2016-10-04 08:36 +0100
    Re: When parameters to printf are in memory jacobnavia <jacob@jacob.remcomp.fr> - 2016-10-02 21:27 +0200

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