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Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide

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James Kuyper <jameskuyper@alumni.caltech.edu> wrote:
> On Sunday, August 16, 2020 at 1:47:58 AM UTC-4, John Forkosh wrote:
> ...
>> Redundancy aside, that n arg is why I originally posted a
>> followup question, asking about calloc() rather than malloc().
>> Although I do typically write
>>     int n = 99; /* or whatever */
>>     typedef Whatever whatever;
>>     whatever *p = (whatever *)malloc(n*sizeof(whatever));
>> there is (or at least there used to be) some potential
>> boundary alignment problem, whereby calloc(n,sizeof(whatever))
>> might be potentially safer. So is boundary alignment never
>> a problem anymore, as of some more recent C, or what?
> 
> It's not particularly recent. The very first version of the C standard,
> from 1989, specifies for malloc(), calloc(), and realloc(), that "The
> pointer returned if the allocation succeeds is suitably aligned so
> that it may be assigned to a pointer to any type of object and then
> used to access such an object in the space allocated (until the space
> is explicitly freed or reallocated)." (4.10.3).
> 
> Prior to that, there was K&R C, which mentioned alloc(), talloc(), and
> calloc(), but never mentioned malloc(). alloc() talloc() were functions
> defined in the text itself as examples, not members of the standard
> library. calloc() was a standard library function, but somewhat
> different from the one that was standardized: it was declared in
> <stdio.h>, and the corresponding deallocation function was cfree().
> 
> Did you develop your programming habits before  1989?

Thanks James (ditto Ben, Kenny, Richard) for followups answering
my question, in the negative, which is good. So I won't be worrying
about that ever again. My first encounter with C was way back in 1983,
working on Chase's videotex/NAPLPS home banking system, Spectrum.
That was implemented using a Vax/VMS 11/780 front end (and IBM 4341
back end), and I'm guessing it's that VMS C where I read about the
malloc alignment problem, though can't recall ever being bitten by it.
   Kind of funny -- that was so long ago that a google search on
chase bank spectrum videotex  coughs up an old out-of-date .ps copy
of my own resume on the very first page of hits. And no other hits
that I could find mentioning the project, although there were over
200 developers working on it for ~3 years.

> The key difference between malloc() and calloc() doesn't have to do with
> alignment, but with initialization. calloc() is required to zero out the
> memory it allocates. On many implementations, the memory allocated by
> malloc() is also zeroed out, but that's not required, and on
> implementations where it isn't, that difference makes malloc() faster
> than calloc().
> 
> There's another difference: the interface to malloc() potentially allows
> allocation of as much of SIZE_MAX bytes (though such an allocation is
> unlikely to succeed). The interface to calloc() potentially allows
> allocation of as many as SIZE_MAX objects, each of size SIZE_MAX.  But
> I'm not aware of any implementation of C for which calloc() can actually
> allocate more memory than malloc(). size_t is normally chosen to have a
> range sufficient to index even the largest array that calloc() can
> allocate, though there's nothing in the standard that requires that.

-- 
John Forkosh  ( mailto:  j@f.com  where j=john and f=forkosh )

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"Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide Lynn McGuire <lynnmcguire5@gmail.com> - 2020-08-12 13:54 -0500
  Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-08-12 12:23 -0700
    Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide Elijah Stone <elronnd@elronnd.net> - 2020-08-12 15:05 -0700
      Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide Richard Damon <Richard@Damon-Family.org> - 2020-08-12 19:15 -0400
        Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide Philipp Klaus Krause <pkk@spth.de> - 2020-08-13 10:36 +0200
          Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide Poprocks <please@replytogroup.com> - 2020-08-13 14:23 +0000
            What do when -Werror gets in your way (Was: "Why the C Language Will Never Stop You from Making Mistakes") by JeanHeyd Meneide gazelle@shell.xmission.com (Kenny McCormack) - 2020-08-13 14:49 +0000
        Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide Elijah Stone <elronnd@elronnd.net> - 2020-08-13 23:25 -0700
      Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide John Forkosh <forkosh@panix.com> - 2020-08-13 01:15 +0000
        Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-08-12 18:42 -0700
          Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide John Forkosh <forkosh@panix.com> - 2020-08-13 06:15 +0000
            Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-08-12 23:23 -0700
              Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide John Forkosh <forkosh@panix.com> - 2020-08-13 06:44 +0000
                Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide Poprocks <please@replytogroup.com> - 2020-08-15 22:51 +0000
                Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide Richard Damon <Richard@Damon-Family.org> - 2020-08-15 19:41 -0400
                Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-08-16 02:02 +0100
                Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide John Forkosh <forkosh@panix.com> - 2020-08-16 05:47 +0000
                Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-08-16 12:03 +0100
                Kinda by definition... (Was: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide) gazelle@shell.xmission.com (Kenny McCormack) - 2020-08-16 11:49 +0000
                Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-08-16 05:33 -0700
                Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide John Forkosh <forkosh@panix.com> - 2020-08-17 06:27 +0000
                Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide Richard Damon <Richard@Damon-Family.org> - 2020-08-16 09:12 -0400
              Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide Richard Damon <Richard@Damon-Family.org> - 2020-08-13 07:38 -0400
                Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-08-13 09:33 -0400
                Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide Richard Damon <Richard@Damon-Family.org> - 2020-08-14 10:50 -0400
                Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-08-14 12:39 -0400
                Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide Richard Damon <Richard@Damon-Family.org> - 2020-08-14 16:53 -0400
                Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-08-14 19:49 -0400
                Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-08-15 02:31 -0700
                Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-08-15 16:10 -0700
                Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide Richard Damon <Richard@Damon-Family.org> - 2020-08-16 09:25 -0400
                Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-08-16 10:50 -0700
                Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-08-16 15:40 -0400
                Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide Richard Damon <Richard@Damon-Family.org> - 2020-08-16 19:39 -0400
                Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-08-16 21:12 -0400
                Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide Richard Harnden <richard.nospam@gmail.com> - 2020-08-18 08:47 +0100
                Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-08-18 08:26 -0400
                Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-08-28 08:10 -0700
              Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide gazelle@shell.xmission.com (Kenny McCormack) - 2020-08-13 12:48 +0000
            Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide John Bode <jfbode1029@gmail.com> - 2020-08-13 09:46 -0700
      Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide Jorgen Grahn <grahn+nntp@snipabacken.se> - 2020-08-13 06:14 +0000
    Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide Anton Shepelev <anton.txt@gmail.com> - 2020-08-13 01:19 +0300
      Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-08-12 16:18 -0700
    Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide Scott Newman <scott69@gmail.com> - 2020-08-13 09:25 +0200
      Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-08-13 00:41 -0700
        Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide Scott Newman <scott69@gmail.com> - 2020-08-13 12:53 +0200
          Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide Richard Harnden <richard.nospam@gmail.com> - 2020-08-13 12:52 +0100
            Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide David Brown <david.brown@hesbynett.no> - 2020-08-13 15:17 +0200
          Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-08-13 10:38 -0700
            Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide Scott Newman <scott69@gmail.com> - 2020-08-13 19:44 +0200
              Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide Bart <bc@freeuk.com> - 2020-08-13 19:10 +0100
              Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-08-13 11:42 -0700
                Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide scott@slp53.sl.home (Scott Lurndal) - 2020-08-14 05:56 +0000
                Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide Bonita Montero <Bonita.Montero@gmail.com> - 2020-08-14 09:14 +0200
                Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-08-14 08:45 -0400
                Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide gazelle@shell.xmission.com (Kenny McCormack) - 2020-08-14 16:51 +0000
            Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide Ian Collins <ian-news@hotmail.com> - 2020-08-15 09:11 +1200
    Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-08-24 16:58 -0700
  Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide Philipp Klaus Krause <pkk@spth.de> - 2020-08-13 10:32 +0200
    Re: "Why the C Language Will Never Stop You from Making Mistakes" by JeanHeyd Meneide Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-08-23 07:04 -0700

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