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| From | jt@toerring.de (Jens Thoms Toerring) |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: malloc and maximum size |
| Date | 2011-10-14 17:10 +0000 |
| Organization | Freie Universitaet Berlin |
| Message-ID | <9fr8ofFhnU2@mid.uni-berlin.de> (permalink) |
| References | <dc9e20a5-6a6b-4a1c-b2d2-5c8bcc50c812@a12g2000vbz.googlegroups.com> |
V.Subramanian, India <subramanian100in@yahoo.com> wrote:
> This question is only for understanding purpose.
> I am using RedHat Linux kenel 2.6.9 on Intel Pentium D dual core
> processor.
> The malloc function takes size_t type argument. I am using gcc 3.4.3
> implementation. Under this implementation, in stdint.h, SIZE_MAX is
> defined as follows:
> # define SIZE_MAX (4294967295U)
> SIZE_MAX, defined in stdint.h, is the largest value that can be
> represented in type size_t. However when I pass SIZE_MAX as the
> argument to malloc, it is unable to allocate SIZE_MAX bytes of memory.
> In fact, malloc allocates much much less memory.
As other's already have pointed out the simple reason for
the result you obtained.
Thus I just want to comment on the lines like
> fprintf(stderr,
> "%u - %u : ",
> SIZE_MAX,
> count);
You're using the '%u' format specifier for a size_t type.
'%u' is meant for unsigned ints. You might get away with
this on your machine when 'size_t' is actually typedef'ed
(or '#define'-ed) to 'unsigned int' but that's not some-
thing you should get used to rely on. E.g. on my machine
SIZE_MAX is 18446744073709551615 and that's much too large
for an unsigned int (UINT_MAX is 4294967295 here and I thus
get compiler warnings). You should, if available, always
use the '%zu' format specifier (introduced in C99) or, if
you are not sure it's available, cast size_t values to the
largest available unsigned int type (at least 'unsigned
long int') and use the appropriate format specifier to be
reasonably sure that what you get printed out is correct.
Regards, Jens
--
\ Jens Thoms Toerring ___ jt@toerring.de
\__________________________ http://toerring.de
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malloc and maximum size "V.Subramanian, India" <subramanian100in@yahoo.com> - 2011-10-14 06:31 -0700
Re: malloc and maximum size gordonb.pey1d@burditt.org (Gordon Burditt) - 2011-10-14 09:45 -0500
Re: malloc and maximum size Lowell Gilbert <lgusenet@be-well.ilk.org> - 2011-10-14 11:10 -0400
Re: malloc and maximum size James Kuyper <jameskuyper@verizon.net> - 2011-10-14 11:40 -0400
Re: malloc and maximum size Lowell Gilbert <lgusenet@be-well.ilk.org> - 2011-10-14 15:00 -0400
Re: malloc and maximum size James Kuyper <jameskuyper@verizon.net> - 2011-10-14 15:17 -0400
Re: malloc and maximum size Lowell Gilbert <lgusenet@be-well.ilk.org> - 2011-10-14 15:46 -0400
Re: malloc and maximum size James Kuyper <jameskuyper@verizon.net> - 2011-10-14 16:38 -0400
Re: malloc and maximum size Ike Naar <ike@iceland.freeshell.org> - 2011-10-14 21:59 +0000
Re: malloc and maximum size James Kuyper <jameskuyper@verizon.net> - 2011-10-14 18:26 -0400
Re: malloc and maximum size Lowell Gilbert <lgusenet@be-well.ilk.org> - 2011-10-14 18:42 -0400
Re: malloc and maximum size Keith Thompson <kst-u@mib.org> - 2011-10-14 16:27 -0700
Re: malloc and maximum size Richard Damon <news.x.richarddamon@xoxy.net> - 2011-10-14 20:41 -0400
Re: malloc and maximum size Keith Thompson <kst-u@mib.org> - 2011-10-14 18:31 -0700
Re: malloc and maximum size Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-10-15 02:58 +0100
Re: malloc and maximum size Keith Thompson <kst-u@mib.org> - 2011-10-14 22:11 -0700
Re: malloc and maximum size James Kuyper <jameskuyper@verizon.net> - 2011-10-14 22:59 -0400
Re: malloc and maximum size Richard Damon <news.x.richarddamon@xoxy.net> - 2011-10-14 23:44 -0400
Re: malloc and maximum size Keith Thompson <kst-u@mib.org> - 2011-10-14 22:56 -0700
Re: malloc and maximum size James Kuyper <jameskuyper@verizon.net> - 2011-10-15 07:52 -0400
Re: malloc and maximum size Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-24 16:54 -0800
Re: malloc and maximum size Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-24 16:51 -0800
Re: malloc and maximum size James Kuyper <jameskuyper@verizon.net> - 2011-10-14 22:51 -0400
Re: malloc and maximum size Keith Thompson <kst-u@mib.org> - 2011-10-14 22:48 -0700
Re: malloc and maximum size James Kuyper <jameskuyper@verizon.net> - 2011-10-15 07:54 -0400
Re: malloc and maximum size Keith Thompson <kst-u@mib.org> - 2011-10-15 11:25 -0700
Re: malloc and maximum size James Kuyper <jameskuyper@verizon.net> - 2011-10-15 21:21 -0400
Re: malloc and maximum size Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-24 17:41 -0800
Re: malloc and maximum size Kaz Kylheku <kaz@kylheku.com> - 2012-01-25 02:11 +0000
Re: malloc and maximum size Richard Damon <news.x.richarddamon@xoxy.net> - 2011-10-15 11:50 -0400
Re: malloc and maximum size James Kuyper <jameskuyper@verizon.net> - 2011-10-15 21:38 -0400
Re: malloc and maximum size Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-24 17:33 -0800
Re: malloc and maximum size Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-24 17:06 -0800
Re: malloc and maximum size Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-24 16:58 -0800
Re: malloc and maximum size Kaz Kylheku <kaz@kylheku.com> - 2012-01-25 01:23 +0000
Re: malloc and maximum size Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-31 16:31 -0800
Re: malloc and maximum size James Kuyper <jameskuyper@verizon.net> - 2011-10-14 22:20 -0400
Re: malloc and maximum size Keith Thompson <kst-u@mib.org> - 2011-10-14 16:03 -0700
Re: malloc and maximum size James Kuyper <jameskuyper@verizon.net> - 2011-10-14 23:01 -0400
Re: malloc and maximum size Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-24 17:35 -0800
Re: malloc and maximum size Kaz Kylheku <kaz@kylheku.com> - 2012-01-25 02:33 +0000
Re: malloc and maximum size Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-31 17:14 -0800
Re: malloc and maximum size Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-24 16:45 -0800
Re: malloc and maximum size Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-24 16:32 -0800
Re: malloc and maximum size Keith Thompson <kst-u@mib.org> - 2012-01-25 02:40 -0800
Re: malloc and maximum size Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-31 17:27 -0800
Re: malloc and maximum size Richard Damon <news.x.richarddamon@xoxy.net> - 2011-10-14 16:17 -0400
Re: malloc and maximum size James Kuyper <jameskuyper@verizon.net> - 2011-10-14 16:52 -0400
Re: malloc and maximum size Keith Thompson <kst-u@mib.org> - 2011-10-14 16:12 -0700
Re: malloc and maximum size James Kuyper <jameskuyper@verizon.net> - 2011-10-14 23:04 -0400
Re: malloc and maximum size Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-24 16:36 -0800
Re: malloc and maximum size Ike Naar <ike@iceland.freeshell.org> - 2011-10-14 16:49 +0000
Re: malloc and maximum size James Kuyper <jameskuyper@verizon.net> - 2011-10-14 11:05 -0400
Re: malloc and maximum size Nobody <nobody@nowhere.com> - 2011-10-14 16:11 +0100
Re: malloc and maximum size Kenneth Brody <kenbrody@spamcop.net> - 2011-10-14 12:24 -0400
Re: malloc and maximum size jt@toerring.de (Jens Thoms Toerring) - 2011-10-14 17:10 +0000
Re: malloc and maximum size Stephen Sprunk <stephen@sprunk.org> - 2011-10-14 13:43 -0500
Re: malloc and maximum size Keith Thompson <kst-u@mib.org> - 2011-10-14 12:03 -0700
Re: malloc and maximum size jt@toerring.de (Jens Thoms Toerring) - 2011-10-14 20:36 +0000
Re: malloc and maximum size Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-24 16:26 -0800
Re: malloc and maximum size Seebs <usenet-nospam@seebs.net> - 2011-10-17 17:21 +0000
Re: malloc and maximum size Shao Miller <sha0.miller@gmail.com> - 2012-01-24 23:49 -0500
Re: malloc and maximum size Shao Miller <sha0.miller@gmail.com> - 2012-01-24 23:55 -0500
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