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From: Lawrence D'Oliveiro <ldo@nz.invalid>
Newsgroups: comp.lang.c
Subject: Re: realloc() - frequency, conditions, or experiences about
 relocation?
Date: Tue, 25 Jun 2024 07:02:39 -0000 (UTC)
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On Mon, 24 Jun 2024 02:55:39 -0700, Keith Thompson wrote:

> Lawrence D'Oliveiro <ldo@nz.invalid> writes:
>>
>> The usual way I use realloc is to maintain separate counts of the
>> number of array elements I have allocated, and the number I am actually
>> using. A realloc call is only needed when the latter hits the former.
>> Every time I call realloc, I will extend by some minimum number of
>> array elements (e.g. 128), roughly comparable to the sort of array size
>> I typically end up with.
>>
>> And then when the structure is complete, I do a final realloc call to
>> shrink it down so the size is actually that used. Is it safe to assume
>> such a call will never fail? Hmm ...
> 
> It's not safe to assume that a shrinking realloc call will never fail.
> It's possible that it will never fail in any existing implementation,
> but the standard makes no such guarantee.
>
> ...
> 
> Having said all that, if realloc fails (indicated by returning a null
> pointer), you still have the original pointer to the object.

In other words, it’s safe to ignore any error from that last shrinking 
realloc? That’s good enough for me. ;)