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Re: [MUDFLAP] Is sizeof(ARRAY[0]) equivalent to sizeof(*ARRAY) ?

From glen herrmannsfeldt <gah@ugcs.caltech.edu>
Newsgroups comp.lang.c
Subject Re: [MUDFLAP] Is sizeof(ARRAY[0]) equivalent to sizeof(*ARRAY) ?
Date 2013-01-14 21:21 +0000
Organization Aioe.org NNTP Server
Message-ID <kd1sta$9jg$1@speranza.aioe.org> (permalink)
References (10 earlier) <kcv9cb$a2g$1@dont-email.me> <lnfw24d55f.fsf@nuthaus.mib.org> <kcviqf$344$1@dont-email.me> <ln7gngd1jz.fsf@nuthaus.mib.org> <kcvo9s$shm$1@dont-email.me>

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Shao Miller <sha0.miller@gmail.com> wrote:

(snip, someone wrote)
>> Who says the loop is for initialization?  It might not even be writing
>> to the array.
 
> I did.  "The loop body for this could very well initialize ten elements 
> at a time, but I'd probably advance 'i' by 1 instead of by 10, and use 
> the '% 10' operator in the loop's body, if need be."  (If you'll forgive 
> the 10 with "operator")  I'm saying "if, then", not making a claim about 
> the loop's purpose.
 
(snip)

> If you are talking about:
 
>   void some_func1(void) {
>       int arr[4];
>       int i;
> 
>       for (i = 0; i < sizeof arr / sizeof arr[0]; i += 10)
>         /* Anything */
>     }
 
> then I'd certainly say it's silly!  We can see right away that the 
> advancement of 'i' is silly!  Consider what kind of code review you'd 
> offer someone about this.

OK, how about:

#define N 4
   void some_func1(void) {
       int arr[N];
       int i;
 
       for (i = 0; i < sizeof arr / sizeof arr[0]; i += 10)
         /* Anything */
     }

Depending on how the preprocessor is implemented, the compiler still
sees 4, but the N could change later.

-- glen

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Thread

[MUDFLAP] Is sizeof(ARRAY[0]) equivalent to sizeof(*ARRAY) ? m.labanowicz@gmail.com - 2013-01-09 07:26 -0800
  Re: [MUDFLAP] Is sizeof(ARRAY[0]) equivalent to sizeof(*ARRAY) ? James Kuyper <jameskuyper@verizon.net> - 2013-01-09 11:30 -0500
  Re: [MUDFLAP] Is sizeof(ARRAY[0]) equivalent to sizeof(*ARRAY) ? Eric Sosman <esosman@comcast-dot-net.invalid> - 2013-01-09 11:58 -0500
    Re: [MUDFLAP] Is sizeof(ARRAY[0]) equivalent to sizeof(*ARRAY) ? Robert Wessel <robertwessel2@yahoo.com> - 2013-01-09 12:27 -0600
    Re: [MUDFLAP] Is sizeof(ARRAY[0]) equivalent to sizeof(*ARRAY) ? Keith Thompson <kst-u@mib.org> - 2013-01-09 11:22 -0800
  Re: [MUDFLAP] Is sizeof(ARRAY[0]) equivalent to sizeof(*ARRAY) ? Shao Miller <sha0.miller@gmail.com> - 2013-01-09 14:39 -0500
  Re: [MUDFLAP] Is sizeof(ARRAY[0]) equivalent to sizeof(*ARRAY) ? m.labanowicz@gmail.com - 2013-01-10 02:40 -0800
    Re: [MUDFLAP] Is sizeof(ARRAY[0]) equivalent to sizeof(*ARRAY) ? Shao Miller <sha0.miller@gmail.com> - 2013-01-10 08:31 -0500
      Re: [MUDFLAP] Is sizeof(ARRAY[0]) equivalent to sizeof(*ARRAY) ? Shao Miller <sha0.miller@gmail.com> - 2013-01-10 08:49 -0500
        Re: [MUDFLAP] Is sizeof(ARRAY[0]) equivalent to sizeof(*ARRAY) ? m.labanowicz@gmail.com - 2013-01-10 06:48 -0800
          Re: [MUDFLAP] Is sizeof(ARRAY[0]) equivalent to sizeof(*ARRAY) ? Shao Miller <sha0.miller@gmail.com> - 2013-01-10 10:33 -0500
      Re: [MUDFLAP] Is sizeof(ARRAY[0]) equivalent to sizeof(*ARRAY) ? Keith Thompson <kst-u@mib.org> - 2013-01-11 08:19 -0800
        Re: [MUDFLAP] Is sizeof(ARRAY[0]) equivalent to sizeof(*ARRAY) ? Shao Miller <sha0.miller@gmail.com> - 2013-01-11 12:46 -0500
          Re: [MUDFLAP] Is sizeof(ARRAY[0]) equivalent to sizeof(*ARRAY) ? Keith Thompson <kst-u@mib.org> - 2013-01-11 14:04 -0800
            Re: [MUDFLAP] Is sizeof(ARRAY[0]) equivalent to sizeof(*ARRAY) ? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2013-01-11 22:42 +0000
              Re: [MUDFLAP] Is sizeof(ARRAY[0]) equivalent to sizeof(*ARRAY) ? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2013-01-12 01:44 +0000
            Re: [MUDFLAP] Is sizeof(ARRAY[0]) equivalent to sizeof(*ARRAY) ? Shao Miller <sha0.miller@gmail.com> - 2013-01-11 19:30 -0500
              Re: [MUDFLAP] Is sizeof(ARRAY[0]) equivalent to sizeof(*ARRAY) ? Shao Miller <sha0.miller@gmail.com> - 2013-01-11 20:11 -0500
              Re: [MUDFLAP] Is sizeof(ARRAY[0]) equivalent to sizeof(*ARRAY) ? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2013-01-12 01:17 +0000
                Re: [MUDFLAP] Is sizeof(ARRAY[0]) equivalent to sizeof(*ARRAY) ? Shao Miller <sha0.miller@gmail.com> - 2013-01-11 20:46 -0500
                Re: [MUDFLAP] Is sizeof(ARRAY[0]) equivalent to sizeof(*ARRAY) ? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2013-01-12 03:14 +0000
                Re: [MUDFLAP] Is sizeof(ARRAY[0]) equivalent to sizeof(*ARRAY) ? Keith Thompson <kst-u@mib.org> - 2013-01-12 14:17 -0800
                Re: [MUDFLAP] Is sizeof(ARRAY[0]) equivalent to sizeof(*ARRAY) ? Shao Miller <sha0.miller@gmail.com> - 2013-01-12 18:02 -0500
                Re: [MUDFLAP] Is sizeof(ARRAY[0]) equivalent to sizeof(*ARRAY) ? Keith Thompson <kst-u@mib.org> - 2013-01-12 15:13 -0800
                Re: [MUDFLAP] Is sizeof(ARRAY[0]) equivalent to sizeof(*ARRAY) ? Shao Miller <sha0.miller@gmail.com> - 2013-01-13 16:36 -0500
                Re: [MUDFLAP] Is sizeof(ARRAY[0]) equivalent to sizeof(*ARRAY) ? Keith Thompson <kst-u@mib.org> - 2013-01-13 15:39 -0800
                Re: [MUDFLAP] Is sizeof(ARRAY[0]) equivalent to sizeof(*ARRAY) ? Shao Miller <sha0.miller@gmail.com> - 2013-01-13 19:17 -0500
                Re: [MUDFLAP] Is sizeof(ARRAY[0]) equivalent to sizeof(*ARRAY) ? Keith Thompson <kst-u@mib.org> - 2013-01-13 16:57 -0800
                Re: [MUDFLAP] Is sizeof(ARRAY[0]) equivalent to sizeof(*ARRAY) ? Shao Miller <sha0.miller@gmail.com> - 2013-01-13 20:50 -0500
                Re: [MUDFLAP] Is sizeof(ARRAY[0]) equivalent to sizeof(*ARRAY) ? Keith Thompson <kst-u@mib.org> - 2013-01-13 19:08 -0800
                Re: [MUDFLAP] Is sizeof(ARRAY[0]) equivalent to sizeof(*ARRAY) ? Shao Miller <sha0.miller@gmail.com> - 2013-01-14 00:00 -0500
                Re: [MUDFLAP] Is sizeof(ARRAY[0]) equivalent to sizeof(*ARRAY) ? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2013-01-14 21:21 +0000
                Re: [MUDFLAP] Is sizeof(ARRAY[0]) equivalent to sizeof(*ARRAY) ? Shao Miller <sha0.miller@gmail.com> - 2013-01-14 17:50 -0500
                Re: [MUDFLAP] Is sizeof(ARRAY[0]) equivalent to sizeof(*ARRAY) ? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2013-01-14 01:23 +0000
                Re: [MUDFLAP] Is sizeof(ARRAY[0]) equivalent to sizeof(*ARRAY) ? Shao Miller <sha0.miller@gmail.com> - 2013-01-13 21:04 -0500
                Re: [MUDFLAP] Is sizeof(ARRAY[0]) equivalent to sizeof(*ARRAY) ? Keith Thompson <kst-u@mib.org> - 2013-01-13 19:13 -0800
                Re: [MUDFLAP] Is sizeof(ARRAY[0]) equivalent to sizeof(*ARRAY) ? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2013-01-14 21:37 +0000
                Re: [MUDFLAP] Is sizeof(ARRAY[0]) equivalent to sizeof(*ARRAY) ? Keith Thompson <kst-u@mib.org> - 2013-01-11 18:28 -0800
              Re: [MUDFLAP] Is sizeof(ARRAY[0]) equivalent to sizeof(*ARRAY) ? Keith Thompson <kst-u@mib.org> - 2013-01-11 18:40 -0800
                Re: [MUDFLAP] Is sizeof(ARRAY[0]) equivalent to sizeof(*ARRAY) ? Shao Miller <sha0.miller@gmail.com> - 2013-01-12 04:30 -0500
    Re: [MUDFLAP] Is sizeof(ARRAY[0]) equivalent to sizeof(*ARRAY) ? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2013-01-10 14:37 +0000
      Re: [MUDFLAP] Is sizeof(ARRAY[0]) equivalent to sizeof(*ARRAY) ? m.labanowicz@gmail.com - 2013-01-10 06:51 -0800
        Re: [MUDFLAP] Is sizeof(ARRAY[0]) equivalent to sizeof(*ARRAY) ? m.labanowicz@gmail.com - 2013-01-10 07:41 -0800
          Re: [MUDFLAP] Is sizeof(ARRAY[0]) equivalent to sizeof(*ARRAY) ? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2013-01-10 16:55 +0000
          Re: [MUDFLAP] Is sizeof(ARRAY[0]) equivalent to sizeof(*ARRAY) ? Shao Miller <sha0.miller@gmail.com> - 2013-01-10 17:41 -0500
            Re: [MUDFLAP] Is sizeof(ARRAY[0]) equivalent to sizeof(*ARRAY) ? m.labanowicz@gmail.com - 2013-01-11 03:03 -0800
              Re: [MUDFLAP] Is sizeof(ARRAY[0]) equivalent to sizeof(*ARRAY) ? m.labanowicz@gmail.com - 2013-01-11 04:14 -0800
                Re: [MUDFLAP] Is sizeof(ARRAY[0]) equivalent to sizeof(*ARRAY) ? James Kuyper <jameskuyper@verizon.net> - 2013-01-11 08:32 -0500

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