NetNews Offline 2/NetNews Offline Volume 2.iso/news/comp/lang/c-part1/7146

Internet Message Format | 1996-08-05 | 1.8 KB

Path: mail2news.demon.co.uk!genesis.demon.co.uk
From: Lawrence Kirby <[e-mail]>
Newsgroups: comp.lang.c
Subject: Re: 'Freeing' storage with realloc
Date: Sat, 17 Feb 96 22:27:06 GMT
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Distribution: world
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References: <4fv44f$[e-mail]>
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In article <4fv44f$[e-mail]>
           [e-mail] "Klaus Berndl" writes:

>
>Please look at the snipped of code:
>
>#include <stdio.h>
>
>main () {
>
>  char* buf = NULL;
>
>  buf = (char*)malloc(100);
>  strcpy(buf, "Klaus Berndl");
>  printf("\n%s\n", buf);
>
>/* line 10 */  buf = (char*)realloc(buf, strlen(buf)+1);  /* line 10 */
>
>  if (buf)
>    printf("\n%s\n", buf);
>  else
>    printf("\nshit!\n");
>}
>
>My questions are now: How much memory is allocated for 'buf' after
>executing line 10?! Does realloc 'freeing' the storage behind byte 13?
>Or are still 100 bytes allocated for buf?

The extra storage is in principle if not in practice freed. All that is
important as far as the program is concerned is that it is illegal to
access buf[13] or beyond after the realloc. Whether a particular
implementation leaves the storage in place is up to the implementation
although any reasonable implementation will make the space available for
further allocation where possible. If you still need to use the space as
part of that array then that call to realloc is inappropriate and should
be removed or changed to a more suitable value.

--
-----------------------------------------
Lawrence Kirby | [e-mail]
Wilts, England | [e-mail]
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