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Groups > comp.lang.c > #138994

Re: A final word on casting.

From Manfred <noname@add.invalid>
Newsgroups comp.lang.c
Subject Re: A final word on casting.
Date 2018-12-23 21:33 +0100
Organization Aioe.org NNTP Server
Message-ID <pvorfk$1t29$1@gioia.aioe.org> (permalink)
References (2 earlier) <87k1k0ie66.fsf@bsb.me.uk> <NaNTD.109597$krL1.91@fx15.am4> <875zvki950.fsf@bsb.me.uk> <fabc96a8-762e-430e-a567-8658f60fe0d5@googlegroups.com> <QdOTD.34006$Ck1.30728@fx18.am4>

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On 12/23/2018 4:55 PM, Bart wrote:

<snip>

> Try this program, which starts from 1.0 then successively ends 0.9, 
> 0.09, 0.009 etc to get progressively longer versions of 1.999...
> 
> It gets closer and closer to 2.0, but is never exactly 2.0:
> 
>    #include <stdio.h>
> 
>    int main (void) {
>      double a,b;
> 
>      a=1.0;
>      b=0.9;
>      for (int i=0; i<30; ++i) {
>          a+=b;
>          printf("a: %.24f, 2.0-a: %.10e, a%s2.0, (int)a: %d, b: %e\n",
>               a, 2.0-a, (a==2.0?"==":"!="), (int)a, b);
>          b/=10.0;
>      }
>    }

Try this instead:

#include <stdio.h>

int main (void) {
   double a,b;

   a=9.0;
   b=0.9;
   for (int i=0; i<30; ++i) {
     a+=b;
     printf("a: %.24f, 10.0-a: %.10e, a%s10.0, (int)a: %d, b: %e\n",
         a, 10.0-a, (a==10.0?"==":"!="), (int)a, b);
     b/=10.0;
   }
}

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Thread

A final word on casting. chanrasjid@gmail.com - 2018-12-23 03:02 -0800
  Re: A final word on casting. Bart <bc@freeuk.com> - 2018-12-23 12:11 +0000
    Re: A final word on casting. Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-12-23 13:08 +0000
      Re: A final word on casting. Bart <bc@freeuk.com> - 2018-12-23 14:43 +0000
        Re: A final word on casting. Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-12-23 14:56 +0000
          Re: A final word on casting. chanrasjid@gmail.com - 2018-12-23 07:08 -0800
            Re: A final word on casting. Bart <bc@freeuk.com> - 2018-12-23 15:55 +0000
              Re: A final word on casting. Bart <bc@freeuk.com> - 2018-12-23 16:07 +0000
              Re: A final word on casting. James Kuyper <jameskuyper@alumni.caltech.edu> - 2018-12-23 08:21 -0800
              Re: A final word on casting. Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-12-23 17:56 +0000
                Re: A final word on casting. Bart <bc@freeuk.com> - 2018-12-23 19:23 +0000
                Re: A final word on casting. Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-12-23 20:12 +0000
                Re: A final word on casting. James Kuyper <jameskuyper@alumni.caltech.edu> - 2018-12-23 14:06 -0800
                Re: A final word on casting. Tim Rentsch <txr@alumni.caltech.edu> - 2018-12-28 09:34 -0800
                Re: A final word on casting. Bart <bc@freeuk.com> - 2018-12-28 20:29 +0000
                Re: A final word on casting. Tim Rentsch <txr@alumni.caltech.edu> - 2018-12-28 15:07 -0800
                Re: A final word on casting. Richard Damon <Richard@Damon-Family.org> - 2018-12-28 20:56 -0500
                Re: A final word on casting. Tim Rentsch <txr@alumni.caltech.edu> - 2018-12-29 09:22 -0800
                Re: A final word on casting. Tim Rentsch <txr@alumni.caltech.edu> - 2019-01-01 13:27 -0800
                Re: A final word on casting. Bart <bc@freeuk.com> - 2019-01-02 01:07 +0000
                Re: A final word on casting. Bart <bc@freeuk.com> - 2019-01-03 18:55 +0000
                Re: A final word on casting. Richard Damon <Richard@Damon-Family.org> - 2019-01-03 22:27 -0500
                Re: A final word on casting. James Kuyper <jameskuyper@alumni.caltech.edu> - 2019-01-04 16:25 -0500
                Re: A final word on casting. Ike Naar <ike@iceland.freeshell.org> - 2018-12-28 19:10 +0000
                Re: A final word on casting. James Kuyper <jameskuyper@alumni.caltech.edu> - 2018-12-28 12:33 -0800
                Re: A final word on casting. "Chris M. Thomasson" <invalid_chris_thomasson@invalid.invalid> - 2018-12-23 14:11 -0800
                Re: A final word on casting. Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2018-12-24 02:54 -0800
                Re: A final word on casting. fir <profesor.fir@gmail.com> - 2018-12-24 03:24 -0800
                Re: A final word on casting. fir <profesor.fir@gmail.com> - 2018-12-24 03:29 -0800
                Re: A final word on casting. fir <profesor.fir@gmail.com> - 2018-12-24 03:45 -0800
                Re: A final word on casting. Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-12-24 13:44 +0000
                Re: A final word on casting. Richard Damon <Richard@Damon-Family.org> - 2018-12-24 08:51 -0500
              Re: A final word on casting. Richard Damon <Richard@Damon-Family.org> - 2018-12-23 14:53 -0500
                Re: A final word on casting. Robert Wessel <robertwessel2@yahoo.com> - 2018-12-24 09:39 -0600
                Re: A final word on casting. Richard Damon <Richard@Damon-Family.org> - 2018-12-24 13:38 -0500
              Re: A final word on casting. Manfred <noname@add.invalid> - 2018-12-23 21:22 +0100
              Re: A final word on casting. Manfred <noname@add.invalid> - 2018-12-23 21:33 +0100
            Re: A final word on casting. James Kuyper <jameskuyper@alumni.caltech.edu> - 2018-12-23 10:56 -0500
              Re: A final word on casting. Sjouke Burry <burrynulnulfour@ppllaanneett.nnll> - 2018-12-23 17:18 +0100
        Re: A final word on casting. Bart <bc@freeuk.com> - 2018-12-23 20:03 +0000
    Re: A final word on casting. "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2018-12-28 14:47 -0500
  Re: A final word on casting. Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-12-23 12:24 +0000
  Re: A final word on casting. Richard Damon <Richard@Damon-Family.org> - 2018-12-23 07:28 -0500
    Re: A final word on casting. Tim Rentsch <txr@alumni.caltech.edu> - 2018-12-28 07:50 -0800
  Re: A final word on casting. fir <profesor.fir@gmail.com> - 2018-12-23 04:35 -0800
    Re: A final word on casting. fir <profesor.fir@gmail.com> - 2018-12-23 04:42 -0800
      Re: A final word on casting. fir <profesor.fir@gmail.com> - 2018-12-23 04:52 -0800
  Re: A final word on casting. James Kuyper <jameskuyper@alumni.caltech.edu> - 2018-12-23 10:28 -0500
  Re: A final word on casting. Barry Schwarz <schwarzb@dqel.com> - 2018-12-23 11:39 -0800
    Re: A final word on casting. Ike Naar <ike@iceland.freeshell.org> - 2018-12-24 07:56 +0000
  Re: A final word on casting. chanrasjid@gmail.com - 2018-12-24 14:03 -0800
    Re: A final word on casting. Barry Schwarz <schwarzb@dqel.com> - 2018-12-24 14:39 -0800
      Re: A final word on casting. chanrasjid@gmail.com - 2018-12-24 14:50 -0800
        Re: A final word on casting. Keith Thompson <kst-u@mib.org> - 2018-12-24 15:34 -0800
      Re: A final word on casting. Keith Thompson <kst-u@mib.org> - 2018-12-24 15:23 -0800
        Re: A final word on casting. chanrasjid@gmail.com - 2018-12-24 20:34 -0800
    Re: A final word on casting. Keith Thompson <kst-u@mib.org> - 2018-12-24 14:52 -0800
      Re: A final word on casting. chanrasjid@gmail.com - 2018-12-24 20:25 -0800
    Re: A final word on casting. James Kuyper <jameskuyper@alumni.caltech.edu> - 2018-12-24 17:52 -0500
    Re: A final word on casting. luser droog <luser.droog@gmail.com> - 2018-12-24 21:27 -0800
      Re: A final word on casting. luser droog <luser.droog@gmail.com> - 2018-12-24 21:39 -0800
      Re: A final word on casting. chanrasjid@gmail.com - 2018-12-24 22:36 -0800

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