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


Groups > comp.lang.c > #73302

Re: Pointers, constant values

From Keith Thompson <kst-u@mib.org>
Newsgroups comp.lang.c
Subject Re: Pointers, constant values
Date 2015-10-19 08:40 -0700
Organization None to speak of
Message-ID <lnpp0azx1o.fsf@kst-u.example.com> (permalink)
References (15 earlier) <87zizgmohd.fsf@bsb.me.uk> <mvvum2$f1b$1@dont-email.me> <87wpujlt5f.fsf@bsb.me.uk> <n016ml$akq$1@dont-email.me> <87k2qjlm80.fsf@bsb.me.uk>

Show all headers | View raw


Ben Bacarisse <ben.usenet@bsb.me.uk> writes:
[...]
> And in Ada (though I'm less sure if this is really idiomatic):
>
>   function Amax(A: IntArray) return Integer is
>       L: Natural := A'Last - A'First + 1;
>    begin
>       if L > 1 then
>          return Integer'Max(Amax(A(A'First .. A'First + L/2 - 1)),
>                             Amax(A(A'First + L/2 .. A'Last)));
>       else
>          return A(A'First);
>       end if;
>    end amax;

You can drop L and use A'Length.

The function will die (raise the Constraint_Error exception)
if you give it an empty array, which is perfectly legal in Ada.
Perhaps that's sensible thing for it to do, but it's probably
cleaner to do it explicitly with a `raise` statement.

The point is that Ada supports "array slices".  Ada array indexing is
not defined in terms of pointer arithmetic.  Arrays can be passed as
parameters, and the A'First, A'Last, and A'Length attributes work on
parameters the same way as on any other array objects. Given an array A,
the slice A(X..Y) is an array object consisting of the elements of A
from indices X to Y, inclusive.

[...]

-- 
Keith Thompson (The_Other_Keith) kst-u@mib.org  <http://www.ghoti.net/~kst>
Working, but not speaking, for JetHead Development, Inc.
"We must do something.  This is something.  Therefore, we must do this."
    -- Antony Jay and Jonathan Lynn, "Yes Minister"

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


Thread

Pointers, constant values Alla _ <modelling.data@gmail.com> - 2015-10-16 00:49 -0700
  Re: Pointers, constant values Philip Lantz <prl@canterey.us> - 2015-10-16 01:49 -0700
  Re: Pointers, constant values James Kuyper <jameskuyper@verizon.net> - 2015-10-16 09:41 -0400
    Re: Pointers, constant values supercat@casperkitty.com - 2015-10-16 08:55 -0700
  Re: Pointers, constant values Keith Thompson <kst-u@mib.org> - 2015-10-16 08:25 -0700
    Re: Pointers, constant values supercat@casperkitty.com - 2015-10-16 09:11 -0700
      Re: Pointers, constant values Keith Thompson <kst-u@mib.org> - 2015-10-16 12:06 -0700
        Re: Pointers, constant values supercat@casperkitty.com - 2015-10-16 12:55 -0700
    Re: Pointers, constant values Bartc <bc@freeuk.com> - 2015-10-16 17:49 +0100
      Re: Pointers, constant values Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2015-10-16 13:23 -0400
        Re: Pointers, constant values Bartc <bc@freeuk.com> - 2015-10-16 19:34 +0100
          Re: Pointers, constant values supercat@casperkitty.com - 2015-10-16 12:05 -0700
        Re: Pointers, constant values Keith Thompson <kst-u@mib.org> - 2015-10-16 12:18 -0700
      Re: Pointers, constant values Keith Thompson <kst-u@mib.org> - 2015-10-16 12:13 -0700
        Re: Pointers, constant values Bartc <bc@freeuk.com> - 2015-10-16 20:33 +0100
          Re: Pointers, constant values Keith Thompson <kst-u@mib.org> - 2015-10-16 13:01 -0700
            Re: Pointers, constant values Bartc <bc@freeuk.com> - 2015-10-16 21:09 +0100
              Re: Pointers, constant values Keith Thompson <kst-u@mib.org> - 2015-10-16 13:41 -0700
          Re: Pointers, constant values Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-10-16 21:07 +0100
            Re: Pointers, constant values Bartc <bc@freeuk.com> - 2015-10-16 21:20 +0100
              Re: Pointers, constant values Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-10-16 22:02 +0100
                Re: Pointers, constant values Bartc <bc@freeuk.com> - 2015-10-16 22:21 +0100
                Re: Pointers, constant values supercat@casperkitty.com - 2015-10-16 14:39 -0700
                Re: Pointers, constant values Keith Thompson <kst-u@mib.org> - 2015-10-16 15:26 -0700
                Re: Pointers, constant values supercat@casperkitty.com - 2015-10-16 15:44 -0700
                Re: Pointers, constant values Keith Thompson <kst-u@mib.org> - 2015-10-16 16:58 -0700
                Re: Pointers, constant values supercat@casperkitty.com - 2015-10-16 17:28 -0700
                Re: Pointers, constant values Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-10-16 22:50 +0100
                Re: Pointers, constant values supercat@casperkitty.com - 2015-10-16 15:14 -0700
                Re: Pointers, constant values Bartc <bc@freeuk.com> - 2015-10-17 01:23 +0100
                Re: Pointers, constant values Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-10-17 19:39 +0100
                Re: Pointers, constant values Bartc <bc@freeuk.com> - 2015-10-17 22:42 +0100
                Re: Pointers, constant values Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-10-18 00:31 +0100
                Re: Pointers, constant values Bartc <bc@freeuk.com> - 2015-10-18 02:11 +0100
                Re: Pointers, constant values Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-10-18 11:59 +0100
                Re: Pointers, constant values Bartc <bc@freeuk.com> - 2015-10-18 12:12 +0100
                Re: Pointers, constant values Bartc <bc@freeuk.com> - 2015-10-18 12:28 +0100
                Re: Pointers, constant values Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-10-18 23:16 +0100
                Re: Pointers, constant values Bartc <bc@freeuk.com> - 2015-10-18 23:34 +0100
                Re: Pointers, constant values Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-10-19 01:45 +0100
                Re: Pointers, constant values Bartc <bc@freeuk.com> - 2015-10-19 11:51 +0100
                Re: Pointers, constant values Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-10-19 12:55 +0100
                Re: Pointers, constant values Bartc <bc@freeuk.com> - 2015-10-19 13:51 +0100
                Re: Pointers, constant values Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-10-19 06:02 -0700
                Re: Pointers, constant values supercat@casperkitty.com - 2015-10-19 07:02 -0700
                Re: Pointers, constant values Bartc <bc@freeuk.com> - 2015-10-19 15:39 +0100
                Re: Pointers, constant values supercat@casperkitty.com - 2015-10-19 08:54 -0700
                Re: Pointers, constant values Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-10-19 09:14 -0700
                Re: Pointers, constant values supercat@casperkitty.com - 2015-10-19 10:21 -0700
                Re: Pointers, constant values Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-10-19 12:57 -0700
                Re: Pointers, constant values glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-10-19 21:20 +0000
                Re: Pointers, constant values supercat@casperkitty.com - 2015-10-20 20:50 -0700
                Re: Pointers, constant values glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-10-21 04:58 +0000
                Re: Pointers, constant values Keith Thompson <kst-u@mib.org> - 2015-10-19 08:40 -0700
                Re: Pointers, constant values Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-10-19 20:17 +0100
                Re: Pointers, constant values supercat@casperkitty.com - 2015-10-17 16:44 -0700
                Re: Pointers, constant values Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-10-18 11:52 +0100
                Re: Pointers, constant values Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-10-18 05:15 -0700
                Re: Pointers, constant values Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-10-18 21:54 +0100
                Re: Pointers, constant values Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-10-18 16:09 -0700
                Re: Pointers, constant values supercat@casperkitty.com - 2015-10-18 07:55 -0700
                Re: Pointers, constant values Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-10-18 21:47 +0100
                Re: Pointers, constant values supercat@casperkitty.com - 2015-10-18 15:37 -0700
                Re: Pointers, constant values Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-10-19 00:10 +0100
                Re: Pointers, constant values supercat@casperkitty.com - 2015-10-18 19:04 -0700
        Re: Pointers, constant values Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-10-16 21:13 +0100
      Re: Pointers, constant values Ian Collins <ian-news@hotmail.com> - 2015-10-17 11:27 +1300
        Re: Pointers, constant values Bartc <bc@freeuk.com> - 2015-10-17 00:56 +0100
  Re: Pointers, constant values Les Cargill <lcargill99@comcast.com> - 2015-10-16 12:37 -0500
    Re: Pointers, constant values James Kuyper <jameskuyper@verizon.net> - 2015-10-16 14:22 -0400
  Re: Pointers, constant values Jorgen Grahn <grahn+nntp@snipabacken.se> - 2015-10-16 18:57 +0000
    Re: Pointers, constant values Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-10-16 20:40 +0100
      Re: Pointers, constant values Jorgen Grahn <grahn+nntp@snipabacken.se> - 2015-10-16 20:46 +0000
        Re: Pointers, constant values Keith Thompson <kst-u@mib.org> - 2015-10-16 14:24 -0700
          Re: Pointers, constant values Jorgen Grahn <grahn+nntp@snipabacken.se> - 2015-10-19 12:43 +0000
  Re: Pointers, constant values Siri Cruz <chine.bleu@yahoo.com> - 2015-10-16 13:20 -0700
    Re: Pointers, constant values supercat@casperkitty.com - 2015-10-17 13:59 -0700

csiph-web