Re: realloc() - frequency, conditions, or experiences about relocation?

From	Keith Thompson <Keith.S.Thompson+u@gmail.com>
Newsgroups	comp.lang.c
Subject	Re: realloc() - frequency, conditions, or experiences about relocation?
Date	2024-06-28 04:04 -0700
Organization	None to speak of
Message-ID	<87le2pxr8v.fsf@nosuchdomain.example.com> (permalink)
References	(4 earlier) <v5bbd3$rhao$2@dont-email.me> <875xtyu0kk.fsf@nosuchdomain.example.com> <v5dq2e$1eh23$11@dont-email.me> <87frt1tk0z.fsf@nosuchdomain.example.com> <87le2p5wd9.fsf@fatphil.org>

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Phil Carmody <pc+usenet@asdf.org> writes:
> Keith Thompson <Keith.S.Thompson+u@gmail.com> writes:
>> Suppose you do something like:
>>
>>     some_type *p = malloc(BIG_VALUE);
>>     // ...
>>     p = realloc(p, SMALL_VALUE);
>>
>> ...  If realloc() succeeds and *does* relocate the object, p
>> still points to memory that has now been deallocated, and you don't have
>> a pointer to the newly allocated memory.
>
> Surely some mistake?

Yes, and thanks for catching it.

If realloc() succeeds, p points to the newly allocated memory; you no
longer have a pointer to the old deallocated memory, but that's a good
thing.

I think I was describing the behavior of calling realloc(p, SMALL_VALUE)
without assigning the result to anything.

> However, such self-assignments are bad for the reasons you state later;
> verify, then update.

Right.

-- 
Keith Thompson (The_Other_Keith) Keith.S.Thompson+u@gmail.com
void Void(void) { Void(); } /* The recursive call of the void */

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Re: realloc() - frequency, conditions, or experiences about relocation? Vir Campestris <vir.campestris@invalid.invalid> - 2024-06-20 21:08 +0100
  Re: realloc() - frequency, conditions, or experiences about relocation? Bonita Montero <Bonita.Montero@gmail.com> - 2024-06-21 21:12 +0200
    Re: realloc() - frequency, conditions, or experiences about relocation? Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-06-24 08:40 +0000
      Re: realloc() - frequency, conditions, or experiences about relocation? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-06-24 02:55 -0700
        Re: realloc() - frequency, conditions, or experiences about relocation? David Brown <david.brown@hesbynett.no> - 2024-06-24 13:40 +0200
          Re: realloc() - frequency, conditions, or experiences about relocation? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-06-24 18:50 +0100
            Re: realloc() - frequency, conditions, or experiences about relocation? scott@slp53.sl.home (Scott Lurndal) - 2024-06-24 18:20 +0000
              Re: realloc() - frequency, conditions, or experiences about relocation? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-06-24 14:28 -0700
                Re: realloc() - frequency, conditions, or experiences about relocation? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-06-25 00:22 +0100
                Re: realloc() - frequency, conditions, or experiences about relocation? "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-06-24 18:31 -0700
            Re: realloc() - frequency, conditions, or experiences about relocation? Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-06-25 07:06 +0000
              Re: realloc() - frequency, conditions, or experiences about relocation? Bonita Montero <Bonita.Montero@gmail.com> - 2024-06-25 10:38 +0200
                Re: realloc() - frequency, conditions, or experiences about relocation? Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-06-26 00:51 +0000
          Re: realloc() - frequency, conditions, or experiences about relocation? "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-06-24 12:33 -0700
            Re: realloc() - frequency, conditions, or experiences about relocation? Bonita Montero <Bonita.Montero@gmail.com> - 2024-06-24 21:48 +0200
          Re: realloc() - frequency, conditions, or experiences about relocation? Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-06-24 22:59 +0000
        Re: realloc() - frequency, conditions, or experiences about relocation? Bonita Montero <Bonita.Montero@gmail.com> - 2024-06-24 16:19 +0200
        Re: realloc() - frequency, conditions, or experiences about relocation? Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-06-25 07:02 +0000
          Re: realloc() - frequency, conditions, or experiences about relocation? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-06-25 03:05 -0700
            Re: realloc() - frequency, conditions, or experiences about relocation? Richard Damon <richard@damon-family.org> - 2024-06-25 07:21 -0400
            Re: realloc() - frequency, conditions, or experiences about relocation? Phil Carmody <pc+usenet@asdf.org> - 2024-06-28 11:01 +0300
              Re: realloc() - frequency, conditions, or experiences about relocation? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-06-28 04:04 -0700
            Re: realloc() - frequency, conditions, or experiences about relocation? James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-06-28 06:37 -0400
              Re: realloc() - frequency, conditions, or experiences about relocation? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-06-28 04:05 -0700
          Re: realloc() - frequency, conditions, or experiences about relocation? James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-06-28 06:36 -0400
      Re: realloc() - frequency, conditions, or experiences about relocation? Bonita Montero <Bonita.Montero@gmail.com> - 2024-06-24 16:16 +0200
        Down the hall, past the water cooler, third door on the left... (Was: realloc() - frequency, conditions, or experiences about) relocation? gazelle@shell.xmission.com (Kenny McCormack) - 2024-06-24 15:44 +0000
          Re: Down the hall, past the water cooler, third door on the left... (Was: realloc() - frequency, conditions, or experiences about) relocation? Bonita Montero <Bonita.Montero@gmail.com> - 2024-06-24 20:16 +0200

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