From: "Steve" <nospam_steved94@comcast.net>
Subject: Re: memory management
Date: Thu, 2 Jun 2005 18:41:07 -0700
Date: 2005-06-02T18:41:07-07:00 [thread overview]
Message-ID: <M-GdnSTkAoGSKALfRVn-vQ@comcast.com> (raw)
In-Reply-To: wccoeav8tin.fsf@shell01.TheWorld.com
"Robert A Duff" <bobduff@shell01.TheWorld.com> wrote in message
news:wccoeav8tin.fsf@shell01.TheWorld.com...
[snip]
> When I say "pointer", I don't mean it has to be implemented as a single
> machine address. It could be an offset from some known base address, an
> index into an array, or (as you say) a fat pointer -- among other
> things.
>
> The same is true of pointers in C and C++ -- an implementation is free
> to implement pointers as something other than a machine address. In
> fact, if a C compiler wishes to check array bounds, it pretty much *has*
> to use fat pointers. I know of one C compiler that did just that. My
> point is that "pointer" is not synonymous with "single machine address",
> even in C.
While some C/C++ compilers may have checked array bounds, I'm not so sure it
complies with a standard. I don't have a copy of the standard available to
check.
I do know that it is a common C idiom to describe a structure something
like:
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;
}
Which would not work if array bounds were checked.
I have heard of tools that will do array bounds checking with C, that give
some way of describing the above example, but I don't think it is really
part of the C/C++ standard.
I'm suprised the compiler that did check array bounds was validated... oh
wait a minute ;-)
Steve
(The Duck)
next prev parent reply other threads:[~2005-06-03 1:41 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 [this message]
2005-06-03 10:12 ` alex goldman
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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