Re: C programming in 2011

From	James Kuyper <jameskuyper@verizon.net>
Newsgroups	comp.lang.c
Subject	Re: C programming in 2011
Date	2011-06-03 06:49 -0400
Organization	A noiseless patient Spider
Message-ID	<isae8i$ppm$1@dont-email.me> (permalink)
References	(13 earlier) <slrniuf4ro.29uo.willem@toad.stack.nl> <d8dbcda0-d601-45cb-9c8b-f1066098516c@r20g2000yqd.googlegroups.com> <slrniufrmn.24j2.usenet-nospam@guild.seebs.net> <f9c06a9e-e8f4-41b1-bfa8-06e70b7a39e2@k16g2000yqm.googlegroups.com> <slrniuh79k.37q.angel+news@pearlgates.net>

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On 06/03/2011 04:37 AM, Angel wrote:
...
> "unsigned integer" is a human interpretation, a computer works only with
> bits. You're right in claiming that unsigned int is the most practical
> way of making the program counter visible to humans, but the mere
> existence of a program counter is no proof that the implementation
> supports unsigned integer calculations. Jumps and branches are implemented
> in the hardware wiring, not in some arithmetic unit.

The interpretation need not be completely arbitrary. Let's assume, for
the sake of keeping the numbers small, a machine with 32-bit addresses.
Interpreting the addresses as unsigned integers implies that the piece
of memory with an address whose address is 0x7FFFFFFF is "close", in
some sense, to the one whose address is 0x80000000. Interpreting them
with signed integers implies that the memory with an address of -1 is
"close" to the memory with an address of 0. In what sense are they
"close"? That varies from platform to platform, and there doesn't have
to be any meaningful concept of some memory addresses being closer
together than others. However, one way of measuring closeness would be
in terms of how many times you must either decrement or increment an one
address, in order to reach the other address. Keith suggested one
possibility, trapping on overflow, which would make the minimum and
maximum addresses very far apart by this measure. If address arithmetic
traps on overflow, it makes a big difference whether it overflows when
the bit pattern is 0x7FFFFFFF (signed), or 0xFFFFFFFF (unsigned).

If addresses are interpreted as signed integers with 1's complement or
sign-magnitude representations, the consequences are even stronger. The
bit pattern which would represent a negative zero must either be an
invalid address, or a second way of representing the same location in
memory as the bit pattern representing a positive zero.
-- 
James Kuyper

Thread

C programming in 2011 Duncan Bayne <dhgbayne@gmail.com> - 2011-05-25 20:27 -0700
  Re: C programming in 2011 Shao Miller <sha0.miller@gmail.com> - 2011-05-25 22:33 -0500
  Re: C programming in 2011 Duncan Bayne <dhgbayne@gmail.com> - 2011-05-25 20:58 -0700
    Re: C programming in 2011 Duncan Bayne <dhgbayne@gmail.com> - 2011-05-25 21:06 -0700
      Re: C programming in 2011 Shao Miller <sha0.miller@gmail.com> - 2011-05-25 23:24 -0500
  Re: C programming in 2011 Angel <angel+news@spamcop.net> - 2011-05-26 07:51 +0000
    Re: C programming in 2011 Chris H <chris@phaedsys.org> - 2011-05-26 11:15 +0100
      Re: C programming in 2011 James Kuyper <jameskuyper@verizon.net> - 2011-05-26 06:53 -0400
        Re: C programming in 2011 Ian Collins <ian-news@hotmail.com> - 2011-05-27 09:12 +1200
      Re: C programming in 2011 Nizumzen <chicken@mcnuggets.com> - 2011-05-29 00:39 +0100
        Re: C programming in 2011 Noob <root@127.0.0.1> - 2011-06-01 17:38 +0200
          Re: C programming in 2011 Nizumzen <chicken@mcnuggets.com> - 2011-06-01 22:34 +0100
            Re: C programming in 2011 Angel <angel+news@spamcop.net> - 2011-06-01 21:42 +0000
              Re: C programming in 2011 Nizumzen <chicken@mcnuggets.com> - 2011-06-02 00:33 +0100
    Re: C programming in 2011 Duncan Bayne <dhgbayne@gmail.com> - 2011-05-26 03:41 -0700
      Re: C programming in 2011 Jorgen Grahn <grahn+nntp@snipabacken.se> - 2011-05-28 00:46 +0000
    Re: C programming in 2011 Chad <cdalten@gmail.com> - 2011-05-26 14:09 -0700
      Re: C programming in 2011 Keith Thompson <kst-u@mib.org> - 2011-05-26 15:07 -0700
      Re: C programming in 2011 Angel <angel+news@spamcop.net> - 2011-05-27 07:42 +0000
      Re: C programming in 2011 James Kuyper <jameskuyper@verizon.net> - 2011-05-27 07:30 -0400
    Re: C programming in 2011 Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2011-05-29 01:15 +0300
      Re: C programming in 2011 Angel <angel+news@spamcop.net> - 2011-05-28 22:24 +0000
        Re: C programming in 2011 Keith Thompson <kst-u@mib.org> - 2011-05-28 16:08 -0700
          Re: C programming in 2011 Angel <angel+news@spamcop.net> - 2011-05-28 23:47 +0000
            Re: C programming in 2011 Geoff <geoff@invalid.invalid> - 2011-05-28 16:58 -0700
              Re: C programming in 2011 Keith Thompson <kst-u@mib.org> - 2011-05-28 18:49 -0700
                Re: C programming in 2011 Pierre Habouzit <madcoder@debian.org> - 2011-05-29 11:13 +0000
                Re: C programming in 2011 Jorge <jorge@jorgechamorro.com> - 2011-06-04 08:05 -0700
                Re: C programming in 2011 Angel <angel+news@spamcop.net> - 2011-06-04 16:20 +0000
                Re: C programming in 2011 Nizumzen <chicken@mcnuggets.com> - 2011-05-29 14:35 +0100
                Re: C programming in 2011 Keith Thompson <kst-u@mib.org> - 2011-05-29 12:49 -0700
                OT: Brackets, parentheses, etc. (Was: C programming in 2011) Shao Miller <sha0.miller@gmail.com> - 2011-05-29 16:13 -0500
                Re: OT: Brackets, parentheses, etc. (Was: C programming in 2011) "Morris Keesan" <mkeesan@post.harvard.edu> - 2011-05-30 12:17 -0400
                Re: OT: Brackets, parentheses, etc. (Was: C programming in 2011) Shao Miller <sha0.miller@gmail.com> - 2011-05-30 12:52 -0500
                Re: C programming in 2011 Nizumzen <chicken@mcnuggets.com> - 2011-05-29 23:58 +0100
                Re: C programming in 2011 Chris H <chris@phaedsys.org> - 2011-05-30 14:42 +0100
                Re: C programming in 2011 Nizumzen <chicken@mcnuggets.com> - 2011-05-30 17:40 +0100
                Re: C programming in 2011 Sjouke Burry <burrynulnulfour@ppllaanneett.nnll> - 2011-05-30 22:38 +0200
                Re: C programming in 2011 "J. J. Farrell" <jjf@bcs.org.uk> - 2011-05-30 00:38 +0100
                Re: C programming in 2011 Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2011-05-30 11:14 +0300
              Re: C programming in 2011 Malcolm McLean <malcolm.mclean5@btinternet.com> - 2011-05-29 06:55 -0700
            Re: C programming in 2011 Keith Thompson <kst-u@mib.org> - 2011-05-28 18:47 -0700
              Re: C programming in 2011 Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2011-05-30 15:02 +0300
        Re: C programming in 2011 Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2011-05-30 11:01 +0300
          Re: C programming in 2011 Angel <angel+news@spamcop.net> - 2011-05-30 08:51 +0000
            Re: C programming in 2011 Nobody <nobody@nowhere.com> - 2011-05-31 01:54 +0100
              Re: C programming in 2011 Angel <angel+news@spamcop.net> - 2011-05-31 12:00 +0000
                Re: C programming in 2011 Seebs <usenet-nospam@seebs.net> - 2011-05-31 16:44 +0000
                Re: C programming in 2011 Keith Thompson <kst-u@mib.org> - 2011-05-31 11:43 -0700
  Re: C programming in 2011 Chris H <chris@phaedsys.org> - 2011-05-26 11:13 +0100
  Re: C programming in 2011 Francois Grieu <fgrieu@gmail.com> - 2011-05-26 16:04 +0200
    Re: C programming in 2011 Branimir Maksimovic <bmaxa@hotmail.com> - 2011-05-26 16:21 +0200
      Re: C programming in 2011 Francois Grieu <fgrieu@gmail.com> - 2011-05-26 17:23 +0200
        Re: C programming in 2011 Branimir Maksimovic <bmaxa@hotmail.com> - 2011-05-26 19:15 +0200
          Re: C programming in 2011 Willem <willem@toad.stack.nl> - 2011-05-26 17:29 +0000
            Re: C programming in 2011 Branimir Maksimovic <bmaxa@hotmail.com> - 2011-05-26 20:10 +0200
          Re: C programming in 2011 Pierre Habouzit <madcoder@debian.org> - 2011-05-26 17:35 +0000
            Re: C programming in 2011 Willem <willem@toad.stack.nl> - 2011-05-26 17:53 +0000
              Re: C programming in 2011 Malcolm McLean <malcolm.mclean5@btinternet.com> - 2011-05-26 11:13 -0700
                Re: C programming in 2011 James Kuyper <jameskuyper@verizon.net> - 2011-05-26 21:57 -0400
                Re: C programming in 2011 Tim Rentsch <txr@alumni.caltech.edu> - 2011-05-31 01:13 -0700
            Re: C programming in 2011 Branimir Maksimovic <bmaxa@hotmail.com> - 2011-05-26 20:06 +0200
          Re: C programming in 2011 Ralf Damaschke <rwspam@gmx.de> - 2011-05-26 17:57 +0000
            Re: C programming in 2011 Keith Thompson <kst-u@mib.org> - 2011-05-26 11:31 -0700
              Re: C programming in 2011 Ralf Damaschke <rwspam@gmx.de> - 2011-05-26 20:43 +0000
                Re: C programming in 2011 Keith Thompson <kst-u@mib.org> - 2011-05-26 14:53 -0700
        Re: C programming in 2011 Tim Rentsch <txr@alumni.caltech.edu> - 2011-05-31 01:03 -0700
          Re: C programming in 2011 "Kleuskes & Moos" <kleuske@xs4all.nl> - 2011-05-31 01:59 -0700
            Re: C programming in 2011 "Kleuskes & Moos" <kleuske@xs4all.nl> - 2011-05-31 02:55 -0700
              Re: C programming in 2011 James Kuyper <jameskuyper@verizon.net> - 2011-05-31 06:36 -0400
                Re: C programming in 2011 "Kleuskes & Moos" <kleuske@xs4all.nl> - 2011-05-31 05:57 -0700
                Re: C programming in 2011 James Kuyper <jameskuyper@verizon.net> - 2011-05-31 09:23 -0400
                Re: C programming in 2011 "Kleuskes & Moos" <kleuske@xs4all.nl> - 2011-05-31 07:50 -0700
                Re: C programming in 2011 Keith Thompson <kst-u@mib.org> - 2011-05-31 11:41 -0700
                Re: C programming in 2011 "Kleuskes & Moos" <kleuske@xs4all.nl> - 2011-06-01 01:46 -0700
                Re: C programming in 2011 Ike Naar <ike@iceland.freeshell.org> - 2011-06-01 10:07 +0000
                Re: C programming in 2011 "Kleuskes & Moos" <kleuske@xs4all.nl> - 2011-06-01 04:12 -0700
                Re: C programming in 2011 "Kleuskes & Moos" <kleuske@xs4all.nl> - 2011-06-01 07:46 -0700
                Re: C programming in 2011 Seebs <usenet-nospam@seebs.net> - 2011-06-01 17:53 +0000
                Re: C programming in 2011 lawrence.jones@siemens.com - 2011-06-01 16:28 -0400
                Re: C programming in 2011 "Kleuskes & Moos" <kleuske@xs4all.nl> - 2011-06-01 23:28 -0700
                Re: C programming in 2011 Uno <Uno@example.invalid> - 2011-06-09 21:24 -0600
                Re: C programming in 2011 James Kuyper <jameskuyper@verizon.net> - 2011-06-01 10:04 -0400
                Re: C programming in 2011 "Kleuskes & Moos" <kleuske@xs4all.nl> - 2011-06-01 08:21 -0700
                Re: C programming in 2011 "Kleuskes & Moos" <kleuske@xs4all.nl> - 2011-06-01 09:37 -0700
                Re: C programming in 2011 James Kuyper <jameskuyper@verizon.net> - 2011-06-01 12:55 -0400
                Re: C programming in 2011 "Kleuskes & Moos" <kleuske@xs4all.nl> - 2011-06-01 11:52 -0700
                Re: C programming in 2011 "J. J. Farrell" <jjf@bcs.org.uk> - 2011-06-02 00:00 +0100
                Re: C programming in 2011 "Kleuskes & Moos" <kleuske@xs4all.nl> - 2011-06-01 23:19 -0700
                Re: C programming in 2011 James Kuyper <jameskuyper@verizon.net> - 2011-06-01 12:53 -0400
                Re: C programming in 2011 "Kleuskes & Moos" <kleuske@xs4all.nl> - 2011-06-01 11:55 -0700
                Re: C programming in 2011 Keith Thompson <kst-u@mib.org> - 2011-06-01 08:41 -0700
                Re: C programming in 2011 Noob <root@127.0.0.1> - 2011-06-01 17:12 +0200
                Re: C programming in 2011 "Kleuskes & Moos" <kleuske@xs4all.nl> - 2011-06-01 09:28 -0700
                Re: C programming in 2011 Keith Thompson <kst-u@mib.org> - 2011-06-01 08:38 -0700
                Re: C programming in 2011 "Kleuskes & Moos" <kleuske@xs4all.nl> - 2011-06-02 01:00 -0700
                Re: C programming in 2011 Willem <willem@toad.stack.nl> - 2011-06-02 09:13 +0000
                Re: C programming in 2011 "Kleuskes & Moos" <kleuske@xs4all.nl> - 2011-06-02 02:52 -0700
                Re: C programming in 2011 Willem <willem@toad.stack.nl> - 2011-06-02 11:41 +0000
                Re: C programming in 2011 "Kleuskes & Moos" <kleuske@xs4all.nl> - 2011-06-02 05:53 -0700
                Re: C programming in 2011 "Kleuskes & Moos" <kleuske@xs4all.nl> - 2011-06-02 06:49 -0700
                Re: C programming in 2011 Willem <willem@toad.stack.nl> - 2011-06-02 14:18 +0000
                Re: C programming in 2011 Seebs <usenet-nospam@seebs.net> - 2011-06-02 21:02 +0000
                Re: C programming in 2011 "Kleuskes & Moos" <kleuske@xs4all.nl> - 2011-06-02 23:55 -0700
                Re: C programming in 2011 Angel <angel+news@spamcop.net> - 2011-06-03 08:37 +0000
                Re: C programming in 2011 James Kuyper <jameskuyper@verizon.net> - 2011-06-03 06:49 -0400
                Re: C programming in 2011 Angel <angel+news@spamcop.net> - 2011-06-03 11:52 +0000
                Re: C programming in 2011 "Kleuskes & Moos" <kleuske@xs4all.nl> - 2011-06-03 11:11 -0700
                Re: C programming in 2011 Angel <angel+news@spamcop.net> - 2011-06-03 18:23 +0000
                Re: C programming in 2011 Seebs <usenet-nospam@seebs.net> - 2011-06-03 18:59 +0000
                Re: C programming in 2011 Angel <angel+news@spamcop.net> - 2011-06-03 19:48 +0000
                Re: C programming in 2011 "Kleuskes & Moos" <kleuske@xs4all.nl> - 2011-06-03 15:02 -0700
                Re: C programming in 2011 Keith Thompson <kst-u@mib.org> - 2011-06-03 12:19 -0700
                Re: C programming in 2011 "Kleuskes & Moos" <kleuske@xs4all.nl> - 2011-06-03 13:40 -0700
                Re: C programming in 2011 Keith Thompson <kst-u@mib.org> - 2011-06-03 15:11 -0700
                Re: C programming in 2011 "Kleuskes & Moos" <kleuske@xs4all.nl> - 2011-06-03 15:24 -0700
                Re: C programming in 2011 Keith Thompson <kst-u@mib.org> - 2011-06-03 15:34 -0700
                Re: C programming in 2011 "Kleuskes & Moos" <kleuske@xs4all.nl> - 2011-06-03 17:10 -0700
                Re: C programming in 2011 Keith Thompson <kst-u@mib.org> - 2011-06-03 17:34 -0700
                Re: C programming in 2011 James Kuyper <jameskuyper@verizon.net> - 2011-06-04 09:47 -0400
                Re: C programming in 2011 James Kuyper <jameskuyper@verizon.net> - 2011-06-02 10:02 -0400
                Re: C programming in 2011 Angel <angel+news@spamcop.net> - 2011-06-02 12:17 +0000
                Re: C programming in 2011 Keith Thompson <kst-u@mib.org> - 2011-06-02 08:48 -0700
                Re: C programming in 2011 "Kleuskes & Moos" <kleuske@xs4all.nl> - 2011-06-02 10:35 -0700
                Re: C programming in 2011 gordonb.jpem8@burditt.org (Gordon Burditt) - 2011-06-05 23:32 -0500
                Re: C programming in 2011 "Kleuskes & Moos" <kleuske@xs4all.nl> - 2011-06-06 00:12 -0700
                Re: C programming in 2011 gordonb.5k8u2@burditt.org (Gordon Burditt) - 2011-06-06 05:18 -0500
                Re: C programming in 2011 "Kleuskes & Moos" <kleuske@xs4all.nl> - 2011-06-06 08:16 -0700
                Re: C programming in 2011 Michael Press <rubrum@pacbell.net> - 2011-06-03 18:06 -0700
                Re: C programming in 2011 gordonb.zourz@burditt.org (Gordon Burditt) - 2011-06-05 21:25 -0500
                Re: C programming in 2011 "Kleuskes & Moos" <kleuske@xs4all.nl> - 2011-06-06 01:14 -0700
                Re: C programming in 2011 gordonb.donaz@burditt.org (Gordon Burditt) - 2011-06-06 04:36 -0500
                Re: C programming in 2011 "Kleuskes & Moos" <kleuske@xs4all.nl> - 2011-06-06 09:02 -0700
                Re: C programming in 2011 gordonb.k6ruq@burditt.org (Gordon Burditt) - 2011-06-06 18:36 -0500
                Re: C programming in 2011 "Kleuskes & Moos" <kleuske@xs4all.nl> - 2011-06-07 10:14 -0700
                Re: C programming in 2011 "J. J. Farrell" <jjf@bcs.org.uk> - 2011-05-31 19:56 +0100
                Re: C programming in 2011 Noob <root@127.0.0.1> - 2011-06-01 14:54 +0200
                Re: C programming in 2011 Angel <angel+news@spamcop.net> - 2011-06-01 13:07 +0000
                Re: C programming in 2011 pete <pfiland@mindspring.com> - 2011-06-01 14:10 -0400
                Re: C programming in 2011 James Kuyper <jameskuyper@verizon.net> - 2011-06-01 19:58 -0400
                Re: C programming in 2011 Willem <willem@toad.stack.nl> - 2011-06-01 09:07 +0000
                Re: C programming in 2011 James Kuyper <jameskuyper@verizon.net> - 2011-06-01 09:29 -0400
                Re: C programming in 2011 David Thompson <dave.thompson2@verizon.net> - 2011-06-07 02:18 -0400
                Re: C programming in 2011 "Kleuskes & Moos" <kleuske@xs4all.nl> - 2011-06-07 09:31 -0700
                Re: C programming in 2011 Patrick Scheible <kkt@zipcon.net> - 2011-06-09 14:55 -0700
              Re: C programming in 2011 Tim Rentsch <txr@alumni.caltech.edu> - 2011-06-01 02:35 -0700
          Re: C programming in 2011 Francois Grieu <fgrieu@gmail.com> - 2011-05-31 21:57 +0200
            Re: C programming in 2011 Francois Grieu <fgrieu@gmail.com> - 2011-05-31 22:03 +0200
  Re: C programming in 2011 Kenneth Brody <kenbrody@spamcop.net> - 2011-05-26 12:27 -0400
  Re: C programming in 2011 Nobody <nobody@nowhere.com> - 2011-05-26 18:02 +0100

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