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From: Vir Campestris <vir.campestris@invalid.invalid>
Newsgroups: comp.lang.c
Subject: Re: realloc() - frequency, conditions, or experiences about
 relocation?
Date: Tue, 25 Jun 2024 11:55:02 +0100
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On 25/06/2024 09:48, Bonita Montero wrote:
> Test this code with your Linux installation. For my installation
> glibc does all realloc()ations in-place. Really surprising for me.
> 
> #include <stdio.h>
> #include <stdlib.h>
> 
> int main()
> {
>      void *p = malloc( 0x100000000 );
>      printf( "%p\n", p );
>      p = realloc( p, 1 );
>      printf( "%p\n", p );
>      malloc( 0x100000000 - 0x10000 );
>      p = realloc( p, 0x100000000 );
>      printf( "%p\n", p );
> }
Try allocating a bunch of little items, and looking at where they are. 
They'll likely be contiguous, or evenly spaced, depending on your 
implementation and what "little" is.

Then resize them all. Some will move.

Andy.
-- 
Your C++ comment up-thread BTW is off-topic here. My favourite C++ 
container is vector, and that has a reserve call so you can keep growing 
the container without lots of reallocations.