From: alex goldman <hello@spamm.er>
Subject: Re: memory management
Date: Fri, 03 Jun 2005 03:12:50 -0700
Date: 2005-06-03T03:12:50-07:00 [thread overview]
Message-ID: <1176609.QemMZIaVxk@yahoo.com> (raw)
In-Reply-To: M-GdnSTkAoGSKALfRVn-vQ@comcast.com
Steve wrote:
> struct Data_Container
> {
> int nbValues;
> int data[1];
> }
>
> ...
> numElements = 100;
> struct Data_Container* dc = malloc( sizeof(Data_Container) + sizeof(int)
> *( numElements - 1));
>
> dc->nbValues = numElements;
> for( i = 0 ; i < dc->nbValues ; i++ )
> {
> dc->data[ i ] = 0;
> }
I think the results of doing this are undefined, according to the standard.
In fact, the section on pointer arithmetic says even something like
int* p = malloc(100*sizeof(int));
p = p + 101; // more than 1 off
p = p - 50;
is allowed to lead to undefined behavior. The pointer doesn't even need to
be dereferenced! So the C standard certainly doesn't forbid bounds
checking. Why C compilers don't come with this feature as an /option/ has
always puzzled me.
next prev parent reply other threads:[~2005-06-03 10:12 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-05-26 0:57 memory management alex goldman
2005-05-26 2:14 ` David C. Hoos, Sr.
2005-05-26 13:21 ` Steve
2005-05-26 18:40 ` alex goldman
2005-05-28 2:13 ` Steve
2005-05-28 5:19 ` Jeffrey Carter
2005-05-28 14:48 ` Steve
2005-05-26 18:47 ` Pascal Obry
2005-05-27 14:33 ` Martin Krischik
2005-05-26 12:10 ` Robert A Duff
2005-05-27 14:31 ` Martin Krischik
2005-05-28 11:44 ` Robert A Duff
2005-05-28 13:03 ` Simon Wright
2005-05-31 12:04 ` Robert A Duff
2005-06-02 15:42 ` Thomas Maier-Komor
2005-06-02 17:05 ` Robert A Duff
2005-06-03 1:41 ` Steve
2005-06-03 10:12 ` alex goldman [this message]
2005-06-13 4:01 ` Dave Thompson
-- strict thread matches above, loose matches on Subject: below --
2005-04-19 20:30 Memory_Management Anh Vo
2005-04-19 1:39 Memory_Management Bini
2005-04-19 9:18 ` Memory_Management Duncan Sands
2005-04-20 1:06 ` Memory_Management Bini
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