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Re: Using fread function

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Malcolm McLean <malcolm.mclean5@btinternet.com> writes:
> On Sunday, January 29, 2017 at 6:07:29 PM UTC, janus wrote:
>> I just noticed that swapping the positions of the inner parameters
>> does not have any material effect on result. That led me to think
>> that "fread" function just multiple the two parameters.
>> 
>> size_t fread(void *ptr, size_t size, size_t nmemb, FILE *stream);
>> 
>> size_t fread(void *ptr,  size_t nmemb, size_t size, FILE *stream);
>> 
>> Is my position correct?
>> 
> Essentially yes.

Essentially no.

>                  Having two parameters is pretty useless and you might as well pass
> in a size of memory buffer you wish to fill. It also tends to encourage code such 
> as
>
>   fread(x, sizeof(double), 10, fp);
>
> which isn't very portable. 

How is that not portable (assuming x points to a chunk of memory big
enough to hold 10 doubles)?

> The only slight advantage is that it tells you how many doubles were read correctly.
> The number of times the information "7 out of 10" is more useful than "not all ten"
> is vanishingly low, however.

If the distinction isn't useful, you can read a single chunk of 10
doubles.  If it is, you can read 10 elements of sizeof(double) bytes
each.  I presume that flexibility is quite intentional.

-- 
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"

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Using fread function janus <emekamicro@gmail.com> - 2017-01-29 10:07 -0800
  Re: Using fread function "James R. Kuyper" <jameskuyper@verizon.net> - 2017-01-29 14:31 -0500
    Re: Using fread function supercat@casperkitty.com - 2017-01-30 08:03 -0800
    Re: Using fread function Tim Rentsch <txr@alumni.caltech.edu> - 2017-02-01 13:59 -0800
      Re: Using fread function jameskuyper@verizon.net - 2017-02-05 11:40 -0800
        Re: Using fread function Tim Rentsch <txr@alumni.caltech.edu> - 2017-02-08 22:04 -0800
          Re: Using fread function jameskuyper@verizon.net - 2017-02-09 05:39 -0800
            Re: Using fread function supercat@casperkitty.com - 2017-02-09 07:47 -0800
              Re: Using fread function Keith Thompson <kst-u@mib.org> - 2017-02-09 09:19 -0800
                Re: Using fread function supercat@casperkitty.com - 2017-02-09 09:55 -0800
                Re: Using fread function Keith Thompson <kst-u@mib.org> - 2017-02-09 12:10 -0800
                Re: Using fread function supercat@casperkitty.com - 2017-02-09 13:01 -0800
              Re: Using fread function Tim Rentsch <txr@alumni.caltech.edu> - 2017-02-12 09:36 -0800
                Re: Using fread function supercat@casperkitty.com - 2017-02-12 10:52 -0800
                Re: Using fread function Tim Rentsch <txr@alumni.caltech.edu> - 2017-02-19 21:19 -0800
                Re: Using fread function supercat@casperkitty.com - 2017-02-20 09:35 -0800
                Re: Using fread function Keith Thompson <kst-u@mib.org> - 2017-02-20 09:52 -0800
                Re: Using fread function supercat@casperkitty.com - 2017-02-20 11:15 -0800
                Re: Using fread function Keith Thompson <kst-u@mib.org> - 2017-02-20 11:45 -0800
                Re: Using fread function "James R. Kuyper" <jameskuyper@verizon.net> - 2017-02-20 15:38 -0500
                Re: Using fread function Tim Rentsch <txr@alumni.caltech.edu> - 2017-02-23 12:12 -0800
                Re: Using fread function jameskuyper@verizon.net - 2017-02-24 10:37 -0800
                Re: Using fread function Tim Rentsch <txr@alumni.caltech.edu> - 2017-02-23 05:04 -0800
                Re: Using fread function supercat@casperkitty.com - 2017-02-23 07:58 -0800
                Re: Using fread function Tim Rentsch <txr@alumni.caltech.edu> - 2017-02-25 11:48 -0800
                Re: Using fread function jameskuyper@verizon.net - 2017-02-25 13:44 -0800
                Re: Using fread function Tim Rentsch <txr@alumni.caltech.edu> - 2017-04-17 13:12 -0700
                Re: Using fread function supercat@casperkitty.com - 2017-04-17 13:50 -0700
            Re: Using fread function Tim Rentsch <txr@alumni.caltech.edu> - 2017-02-12 09:31 -0800
  Re: Using fread function Keith Thompson <kst-u@mib.org> - 2017-01-29 13:14 -0800
  Re: Using fread function Malcolm McLean <malcolm.mclean5@btinternet.com> - 2017-01-30 08:18 -0800
    Re: Using fread function supercat@casperkitty.com - 2017-01-30 08:44 -0800
    Re: Using fread function Keith Thompson <kst-u@mib.org> - 2017-01-30 11:58 -0800
      Re: Using fread function Malcolm McLean <malcolm.mclean5@btinternet.com> - 2017-01-30 13:05 -0800
        Re: Using fread function supercat@casperkitty.com - 2017-01-30 13:39 -0800
        Re: Using fread function Keith Thompson <kst-u@mib.org> - 2017-01-30 13:57 -0800

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