Re: "Death To C"

From	Bartc <bc@freeuk.com>
Newsgroups	comp.lang.c
Subject	Re: "Death To C"
Date	2015-05-06 09:53 +0100
Organization	A noiseless patient Spider
Message-ID	<micko3$bvi$1@dont-email.me> (permalink)
References	(1 earlier) <1d3d39e1-3907-4222-9369-154784461fbd@googlegroups.com> <20150504224134.0e897c71@maxa-pc> <gq6gkapsgtcnsrmulg96q7nvd1v919i5u6@4ax.com> <mia43h$gc2$1@dont-email.me> <pan.2015.05.06.07.10.05.543000@nowhere.invalid>

Show all headers | View raw

On 06/05/2015 08:10, Nobody wrote:
> On Tue, 05 May 2015 10:57:03 +0100, Bartc wrote:
>
>> It's not necessarily slow. If the bounds *are* known, then frequently you
>> will also know that accesses are within bounds:
>>
>> for (i=0; i<=len(A); ++i)
>>      A[i]=0;
>>
>> No bounds checking needed here.
>
> "<="?

Sorry, I'm more used to 1-based code.

But an automatic system would deal with it properly: the compiler would 
either object immediately, or would leave in bounds-checking (maybe the 
loop is exited early, in a more elaborate case, or an indexing operation 
is guarded by a conditional, so perhaps this is what is intended. So 
allow it, but leave in the bounds check in the case the coder has no 
idea what he's doing.)

(It also demonstrates the errorprone nature of C for-loops I'm always 
complaining about. A 'for' that didn't need you to specify the exact 
compare op needed, or better still a 'forall', would have fewer such 
problems.)

-- 
Bartc

Thread

"Death To C" Lynn McGuire <lmc@winsim.com> - 2015-05-04 14:41 -0500
  Re: "Death To C" Melzzzzz <mel@zzzzz.com> - 2015-05-04 22:16 +0200
    Re: "Death To C" Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-05-04 13:26 -0700
      Re: "Death To C" Melzzzzz <mel@zzzzz.com> - 2015-05-04 22:51 +0200
      Re: "Death To C" Bartc <bc@freeuk.com> - 2015-05-04 22:02 +0100
        Re: "Death To C" Melzzzzz <mel@zzzzz.com> - 2015-05-05 00:06 +0200
  Re: "Death To C" Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-05-04 13:22 -0700
    Re: "Death To C" Melzzzzz <mel@zzzzz.com> - 2015-05-04 22:41 +0200
      Re: "Death To C" Robert Wessel <robertwessel2@yahoo.com> - 2015-05-04 20:25 -0500
        Bounds checking in C (Was: "Death To C") gazelle@shell.xmission.com (Kenny McCormack) - 2015-05-05 02:15 +0000
          Re: Bounds checking in C (Was: "Death To C") BGB <cr88192@hotmail.com> - 2015-05-06 10:23 -0500
        Re: "Death To C" Les Cargill <lcargill99@comcast.com> - 2015-05-04 21:36 -0500
          Re: "Death To C" Robert Wessel <robertwessel2@yahoo.com> - 2015-05-05 01:01 -0500
            Re: "Death To C" Les Cargill <lcargill99@comcast.com> - 2015-05-05 12:23 -0500
          Re: "Death To C" CHIN Dihedral <dihedral88888@gmail.com> - 2015-05-05 03:06 -0700
        Re: "Death To C" Ian Collins <ian-news@hotmail.com> - 2015-05-05 17:43 +1200
          Re: "Death To C" Robert Wessel <robertwessel2@yahoo.com> - 2015-05-05 01:00 -0500
            Re: "Death To C" Robert Wessel <robertwessel2@yahoo.com> - 2015-05-05 01:13 -0500
              Re: "Death To C" Ian Collins <ian-news@hotmail.com> - 2015-05-05 19:15 +1200
                Re: "Death To C" Robert Wessel <robertwessel2@yahoo.com> - 2015-05-05 02:41 -0500
                Re: "Death To C" Ian Collins <ian-news@hotmail.com> - 2015-05-05 20:12 +1200
        Re: "Death To C" glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-05-05 06:48 +0000
        Re: "Death To C" Bartc <bc@freeuk.com> - 2015-05-05 10:57 +0100
          Re: "Death To C" asetofsymbols@gmail.com - 2015-05-05 16:53 -0700
          Re: "Death To C" Nobody <nobody@nowhere.invalid> - 2015-05-06 08:10 +0100
            Re: "Death To C" Bartc <bc@freeuk.com> - 2015-05-06 09:53 +0100
              Re: "Death To C" Richard Heathfield <rjh@cpax.org.uk> - 2015-05-06 13:49 +0100
                Re: "Death To C" Bartc <bc@freeuk.com> - 2015-05-06 14:29 +0100
                Re: "Death To C" Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-05-06 09:43 -0700
                Re: "Death To C" Bartc <bc@freeuk.com> - 2015-05-06 18:24 +0100
          Re: "Death To C" asetofsymbols@gmail.com - 2015-05-08 00:44 -0700
            Re: "Death To C" Bartc <bc@freeuk.com> - 2015-05-08 13:49 +0100
    Re: "Death To C" Bartc <bc@freeuk.com> - 2015-05-04 22:15 +0100
      Re: "Death To C" BGB <cr88192@hotmail.com> - 2015-05-08 09:09 -0500
    Re: "Death To C" Stephen Sprunk <stephen@sprunk.org> - 2015-05-04 16:18 -0500
    Re: "Death To C" Ian Collins <ian-news@hotmail.com> - 2015-05-05 12:49 +1200
  Re: "Death To C" raltbos@xs4all.nl (Richard Bos) - 2015-05-08 21:52 +0000
  Re: "Death To C" Merikissa <merikissa@no.spam.net> - 2015-05-10 04:04 +0300
  Re: "Death To C" "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-05-13 08:11 -0700
    Re: "Death To C" David Kleinecke <dkleinecke@gmail.com> - 2015-05-13 10:00 -0700
      Re: "Death To C" Bartc <bc@freeuk.com> - 2015-05-13 18:20 +0100
        Re: "Death To C" David Kleinecke <dkleinecke@gmail.com> - 2015-05-14 10:47 -0700
          Re: "Death To C" "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-05-14 11:09 -0700
          Re: "Death To C" Bartc <bc@freeuk.com> - 2015-05-15 19:21 +0100
            Re: "Death To C" David Kleinecke <dkleinecke@gmail.com> - 2015-05-16 09:10 -0700
              Re: "Death To C" Bartc <bc@freeuk.com> - 2015-05-16 20:45 +0100
                Re: "Death To C" David Kleinecke <dkleinecke@gmail.com> - 2015-05-17 09:38 -0700
        Re: "Death To C" raltbos@xs4all.nl (Richard Bos) - 2015-05-17 10:47 +0000
          Re: "Death To C" Bartc <bc@freeuk.com> - 2015-05-17 12:20 +0100
      Re: "Death To C" "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-05-13 10:24 -0700
        Re: "Death To C" David Brown <david.brown@hesbynett.no> - 2015-05-13 22:01 +0200
    Re: "Death To C" Nobody <nobody@nowhere.invalid> - 2015-05-14 07:48 +0100

csiph-web