Re: size_t, when to use it? (learning)

From	Ike Naar <ike@iceland.freeshell.org>
Newsgroups	comp.lang.c
Subject	Re: size_t, when to use it? (learning)
Date	2014-04-12 06:53 +0000
Organization	A noiseless patient Spider
Message-ID	<slrn3vfslkhoo0.rr8.ike@iceland.freeshell.org> (permalink)
References	(2 earlier) <li6ter$m07$1@speranza.aioe.org> <5346FBFF.9070009@verizon.net> <c4d89df1-dcdf-49e9-89f0-c4b4c3c11a4c@googlegroups.com> <slrn3vfslkgagd.rk9.ike@iceland.freeshell.org> <lnzjjr8xuh.fsf@nuthaus.mib.org>

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On 2014-04-11, Keith Thompson <kst-u@mib.org> wrote:
> Ike Naar <ike@iceland.freeshell.org> writes:
>> On 2014-04-10, Malcolm McLean <malcolm.mclean5@btinternet.com> wrote:
>>> Fixed-point numbers are integers to C, but that's just a reflection of the
>>> fact that C doesn't have any native syntactical sugar for fixed-point
>>> arithmetic.
>>> The other question is whether
>>>
>>> int i;
>>> int N = 100000;
>>> short *photons = malloc(N * sizeof(short));
>>
>> You've tried to allocate space for N pointers-to-short ...
>
> You've mis-read the code.  He's tried to allocate space for N shorts.
>
>>> for(i=0;i<N;i++)
>>>   potons[i] = detectphoton();
>>
>> ... but here you use the space as if it holds N shorts (assuming
>> 'potons' is a typo for 'photons').
>>
>> Did you mean
>>
>>   short *photons = malloc(N * sizeof *short);
>>
>> ? 
>
> No, sizeof *short is a syntax error.
>
> A better way to write the original would be:
>
>     short *photons = malloc(N * sizeof *photons);
>
> but the "sizeof(short)" version is correct.

Yes I misread the code. Sorry for the confusion.

Thread

size_t, when to use it? (learning) G G <gdotone@gmail.com> - 2014-04-10 08:11 -0700
  Re: size_t, when to use it? (learning) James Kuyper <jameskuyper@verizon.net> - 2014-04-10 11:42 -0400
    Re: size_t, when to use it? (learning) G G <gdotone@gmail.com> - 2014-04-10 08:53 -0700
  Re: size_t, when to use it? (learning) Kaz Kylheku <kaz@kylheku.com> - 2014-04-10 16:20 +0000
  Re: size_t, when to use it? (learning) Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-04-10 11:03 -0700
    Re: size_t, when to use it? (learning) Kaz Kylheku <kaz@kylheku.com> - 2014-04-10 18:48 +0000
      Re: size_t, when to use it? (learning) Tim Prince <tprince@computer.org> - 2014-04-10 19:10 -0400
    Re: size_t, when to use it? (learning) glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-04-10 20:03 +0000
      Re: size_t, when to use it? (learning) James Kuyper <jameskuyper@verizon.net> - 2014-04-10 16:15 -0400
        Re: size_t, when to use it? (learning) Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-04-10 13:47 -0700
          Re: size_t, when to use it? (learning) Keith Thompson <kst-u@mib.org> - 2014-04-10 16:27 -0700
          Re: size_t, when to use it? (learning) Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-04-11 01:08 -0700
            Re: size_t, when to use it? (learning) Ian Collins <ian-news@hotmail.com> - 2014-04-11 20:11 +1200
              Re: size_t, when to use it? (learning) Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-04-11 05:06 -0700
                Re: size_t, when to use it? (learning) glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-04-11 17:40 +0000
            Re: size_t, when to use it? (learning) Tim Rentsch <txr@alumni.caltech.edu> - 2014-04-14 18:44 -0700
          Re: size_t, when to use it? (learning) Ike Naar <ike@iceland.freeshell.org> - 2014-04-11 17:44 +0000
            Re: size_t, when to use it? (learning) Keith Thompson <kst-u@mib.org> - 2014-04-11 12:33 -0700
              Re: size_t, when to use it? (learning) Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-04-11 13:23 -0700
                Re: size_t, when to use it? (learning) Tim Rentsch <txr@alumni.caltech.edu> - 2014-04-14 18:48 -0700
                Re: size_t, when to use it? (learning) Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-04-15 00:49 -0700
                Re: size_t, when to use it? (learning) gazelle@shell.xmission.com (Kenny McCormack) - 2014-04-15 08:16 +0000
                Re: size_t, when to use it? (learning) <william@wilbur.25thandClement.com> - 2014-04-18 16:57 -0700
                Re: size_t, when to use it? (learning) glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-04-19 00:25 +0000
                Re: size_t, when to use it? (learning) Kaz Kylheku <kaz@kylheku.com> - 2014-04-19 01:03 +0000
                Re: size_t, when to use it? (learning) Ian Collins <ian-news@hotmail.com> - 2014-04-19 13:04 +1200
                Re: size_t, when to use it? (learning) Keith Thompson <kst-u@mib.org> - 2014-04-18 19:23 -0700
                Re: size_t, when to use it? (learning) <william@wilbur.25thandClement.com> - 2014-04-18 19:32 -0700
                Re: size_t, when to use it? (learning) Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-04-19 03:38 -0700
                Re: size_t, when to use it? (learning) Tim Rentsch <txr@alumni.caltech.edu> - 2014-04-18 09:13 -0700
                Re: size_t, when to use it? (learning) Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-04-18 14:00 -0700
                Re: size_t, when to use it? (learning) Tim Rentsch <txr@alumni.caltech.edu> - 2014-04-20 16:24 -0700
                Re: size_t, when to use it? (learning) Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-04-22 03:36 -0700
              Re: size_t, when to use it? (learning) Ike Naar <ike@iceland.freeshell.org> - 2014-04-12 06:53 +0000
            Re: size_t, when to use it? (learning) Martin Shobe <martin.shobe@yahoo.com> - 2014-04-11 14:42 -0500
              Re: size_t, when to use it? (learning) Ike Naar <ike@iceland.freeshell.org> - 2014-04-12 06:55 +0000
    Re: size_t, when to use it? (learning) G G <gdotone@gmail.com> - 2014-04-10 13:42 -0700
      Re: size_t, when to use it? (learning) James Kuyper <jameskuyper@verizon.net> - 2014-04-10 17:07 -0400
        Re: size_t, when to use it? (learning) G G <gdotone@gmail.com> - 2014-04-10 16:11 -0700
      Re: size_t, when to use it? (learning) Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-04-10 15:08 -0700
        Re: size_t, when to use it? (learning) Keith Thompson <kst-u@mib.org> - 2014-04-10 17:21 -0700
          Re: size_t, when to use it? (learning) gazelle@shell.xmission.com (Kenny McCormack) - 2014-04-11 01:04 +0000
        Re: size_t, when to use it? (learning) Ian Collins <ian-news@hotmail.com> - 2014-04-11 20:06 +1200
    Re: size_t, when to use it? (learning) Tim Rentsch <txr@alumni.caltech.edu> - 2014-04-14 18:33 -0700
    Re: size_t, when to use it? (learning) Rosario193 <Rosario@invalid.invalid> - 2014-04-15 09:37 +0200
  Re: size_t, when to use it? (learning) Ian Collins <ian-news@hotmail.com> - 2014-04-11 20:09 +1200
  Re: size_t, when to use it? (learning) Tim Rentsch <txr@alumni.caltech.edu> - 2014-04-14 18:21 -0700

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