Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.c > #25452

Re: 2D arrays, pointers, and pointer arithmetic: question

Show all headers | View raw

On 08/29/2012 04:05 PM, Edward Rutherford wrote:
> Keith Thompson wrote:
>> `near` and `far`, which are of course non-standard, can result in
>> different pointer types having different sizes.  Passing a `near` or
>> `far` pointer to printf with a "%p" format is likely to give bad results
>> in practice.
> 
> Using near or far pointers in any way at all will invoke an undefined 
> behavior, so I think it's safe to say bad results are likely with or 
> without attempts to printf() such pointers!

Within the context of the C standard, "undefined behavior" means only
that the C standard doesn't define the behavior. If the compiler's
documentation does define the behavior, you should be OK, even if the C
standard doesn't.

However, it's extremely unlikely that a compiler which supports both
near and far pointers would come along with a C standard library who's
printf() allows you to print both types of pointers with the same "%p"
format specifier. That's the "bad results in practice" that he was
talking about.

Back to comp.lang.c | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

2D arrays, pointers, and pointer arithmetic: question gdotone@gmail.com - 2012-08-24 08:28 -0700
  Re: 2D arrays, pointers, and pointer arithmetic: question Adrian Ratnapala <adrian.ratnapala@gmail.com> - 2012-08-24 08:41 -0700
  Re: 2D arrays, pointers, and pointer arithmetic: question James Kuyper <jameskuyper@verizon.net> - 2012-08-24 12:01 -0400
    Re: 2D arrays, pointers, and pointer arithmetic: question 88888 Dihedral <dihedral88888@googlemail.com> - 2012-08-24 11:10 -0700
  Re: 2D arrays, pointers, and pointer arithmetic: question gdotone@gmail.com - 2012-08-27 13:35 -0700
    Re: 2D arrays, pointers, and pointer arithmetic: question James Kuyper <jameskuyper@verizon.net> - 2012-08-27 16:46 -0400
      Re: 2D arrays, pointers, and pointer arithmetic: question Adrian Ratnapala <raka@scooter.fritz.box> - 2012-08-28 19:06 +0000
        Re: 2D arrays, pointers, and pointer arithmetic: question Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-08-28 15:22 -0400
        Re: 2D arrays, pointers, and pointer arithmetic: question James Kuyper <jameskuyper@verizon.net> - 2012-08-28 15:34 -0400
          Re: 2D arrays, pointers, and pointer arithmetic: question Keith Thompson <kst-u@mib.org> - 2012-08-28 14:11 -0700
            Re: 2D arrays, pointers, and pointer arithmetic: question James Kuyper <jameskuyper@verizon.net> - 2012-08-28 17:26 -0400
            Re: 2D arrays, pointers, and pointer arithmetic: question "io_x" <a@b.c.invalid> - 2012-08-29 09:25 +0200
          Re: 2D arrays, pointers, and pointer arithmetic: question Adrian Ratnapala <raka@scooter.fritz.box> - 2012-08-29 07:20 +0000
            Re: 2D arrays, pointers, and pointer arithmetic: question James Kuyper <jameskuyper@verizon.net> - 2012-08-29 07:17 -0400
              Re: 2D arrays, pointers, and pointer arithmetic: question Adrian Ratnapala <raka@scooter.fritz.box> - 2012-08-29 11:41 +0000
            Re: 2D arrays, pointers, and pointer arithmetic: question Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-08-29 08:21 -0400
              Re: 2D arrays, pointers, and pointer arithmetic: question Keith Thompson <kst-u@mib.org> - 2012-08-29 11:37 -0700
                Re: 2D arrays, pointers, and pointer arithmetic: question Edward Rutherford <edward.p.rutherford79@REMOVETHIS.gmail.com> - 2012-08-29 20:05 +0000
                Re: 2D arrays, pointers, and pointer arithmetic: question James Kuyper <jameskuyper@verizon.net> - 2012-08-29 17:27 -0400
                Re: 2D arrays, pointers, and pointer arithmetic: question Keith Thompson <kst-u@mib.org> - 2012-08-29 18:05 -0700
                Re: 2D arrays, pointers, and pointer arithmetic: question Les Cargill <lcargill99@comcast.com> - 2012-08-29 20:14 -0500
                Re: 2D arrays, pointers, and pointer arithmetic: question Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-08-30 04:47 -0700
                Re: 2D arrays, pointers, and pointer arithmetic: question Richard Damon <news.x.richarddamon@xoxy.net> - 2012-09-01 23:47 -0400
                Re: 2D arrays, pointers, and pointer arithmetic: question 88888 Dihedral <dihedral88888@googlemail.com> - 2012-09-02 04:43 -0700
                Re: 2D arrays, pointers, and pointer arithmetic: question Richard Damon <news.x.richarddamon@xoxy.net> - 2012-09-02 23:12 -0400
                Re: 2D arrays, pointers, and pointer arithmetic: question ais523 <ais523@nethack4.org> - 2012-08-30 11:35 +0000
                Re: 2D arrays, pointers, and pointer arithmetic: question ralph <nt_consulting64@yahoo.com> - 2012-08-30 11:17 -0500
                Re: 2D arrays, pointers, and pointer arithmetic: question Keith Thompson <kst-u@mib.org> - 2012-08-30 13:52 -0700
                Re: 2D arrays, pointers, and pointer arithmetic: question Anders Wegge Keller <wegge@wegge.dk> - 2012-08-30 23:13 +0200
                Re: 2D arrays, pointers, and pointer arithmetic: question ralph <nt_consulting64@yahoo.com> - 2012-08-31 16:37 -0500
    Re: 2D arrays, pointers, and pointer arithmetic: question Barry Schwarz <schwarzb@dqel.com> - 2012-08-27 19:45 -0700
      Re: 2D arrays, pointers, and pointer arithmetic: question Keith Thompson <kst-u@mib.org> - 2012-08-27 20:40 -0700
        Re: 2D arrays, pointers, and pointer arithmetic: question Tim Rentsch <txr@alumni.caltech.edu> - 2012-09-07 06:28 -0700

csiph-web