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

Groups > comp.lang.c++ > #77082

Re: arranging items in a array with a sorted pointer-list

Cross-posted to 2 groups.

Followups directed to: comp.lang.c

Show all headers | View raw

On 2020-11-29, Juha Nieminen <nospam@thanks.invalid> wrote:
> In comp.lang.c++ Siri Cruise <chine.bleu@yahoo.com> wrote:
>> This is my code
>> 
>>     int stringcompare ( /*String comparison for qsort.*/
>>         const ptr a, const ptr b
>>     ) {
>>         char **A = a, **B = b;
>>         return strcmp(*A, *B);
>>     }
>
> Ah, I love how in C you just implicitly cast from const void* to
> non-const char** without a worry in the world, happily ignoring
> the compiler warnings, because what does the compiler know anyway?
> It's just a dumb program.

Arguably, you can do this in Your Compiler's C, not in ISO C.  The
diagnostic is required by ISO C, which requires no such implicit cast to
be performed.  The program is not required to successfully translate at
all.

> Also love how the comparator function is non-static, throwing it in the
> global namespace. Better not have any other function with that name
> anywhere else. But how likely is that? After all, "stringcompare" is
> such a unique name. The chances that anybody will ever use that same
> name anywhere are astronomically minuscule.

In fact, stringcompare intrudes into a namespace reserved by ISO C.
Programs which introduce external names beginning with "str" invoke
undefined behavior.

This is given in the "Future library directions" section.

"Function names that begin with str, mem, or wcs and a lowercase letter
may be added to the declarations in the <string.h> header."

In practice, this doesn't happen just in the future; implementors
add their own functions, like strdup (POSIX), strcasecmp (various?),
memchr (GNU) ...

If <string.h> is included, there are additional considerations in the
use of those names, because <string.h> can introduce macros beginning
with str. So this is required:

  #include <string.h>

  #undef stringcompare
  static int stringcompare(...)
  {
    ...
  }

-- 
TXR Programming Language: http://nongnu.org/txr
Music DIY Mailing List:  http://www.kylheku.com/diy
ADA MP-1 Mailing List:   http://www.kylheku.com/mp1

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

Thread

arranging items in a array with a sorted pointer-list Bonita Montero <Bonita.Montero@gmail.com> - 2020-11-28 11:00 +0100
  Re: arranging items in a array with a sorted pointer-list Melzzzzz <Melzzzzz@zzzzz.com> - 2020-11-28 10:49 +0000
    Re: arranging items in a array with a sorted pointer-list Bonita Montero <Bonita.Montero@gmail.com> - 2020-11-28 12:12 +0100
  Re: arranging items in a array with a sorted pointer-list "Alf P. Steinbach" <alf.p.steinbach+usenet@gmail.com> - 2020-11-28 17:34 +0100
    Re: arranging items in a array with a sorted pointer-list Bonita Montero <Bonita.Montero@gmail.com> - 2020-11-28 17:38 +0100
      Re: arranging items in a array with a sorted pointer-list Richard Damon <Richard@Damon-Family.org> - 2020-11-28 13:03 -0500
        Re: arranging items in a array with a sorted pointer-list Tim Woodall <news001@woodall.me.uk> - 2020-11-28 23:40 +0000
  Re: arranging items in a array with a sorted pointer-list Kaz Kylheku <563-365-8930@kylheku.com> - 2020-11-28 18:08 +0000
  Re: arranging items in a array with a sorted pointer-list Tim Woodall <news001@woodall.me.uk> - 2020-11-28 18:13 +0000
  Re: arranging items in a array with a sorted pointer-list Siri Cruise <chine.bleu@yahoo.com> - 2020-11-28 17:16 -0800
    Re: arranging items in a array with a sorted pointer-list Juha Nieminen <nospam@thanks.invalid> - 2020-11-29 09:41 +0000
      Re: arranging items in a array with a sorted pointer-list Siri Cruise <chine.bleu@yahoo.com> - 2020-11-29 02:16 -0800
        Re: arranging items in a array with a sorted pointer-list Kaz Kylheku <563-365-8930@kylheku.com> - 2020-11-29 18:32 +0000
        Re: arranging items in a array with a sorted pointer-list Juha Nieminen <nospam@thanks.invalid> - 2020-11-30 09:01 +0000
      Re: arranging items in a array with a sorted pointer-list Kaz Kylheku <563-365-8930@kylheku.com> - 2020-11-29 18:28 +0000
      Re: arranging items in a array with a sorted pointer-list Richard Damon <Richard@Damon-Family.org> - 2020-11-29 14:01 -0500
        Re: arranging items in a array with a sorted pointer-list Juha Nieminen <nospam@thanks.invalid> - 2020-11-30 09:05 +0000
          Re: arranging items in a array with a sorted pointer-list Richard Damon <Richard@Damon-Family.org> - 2020-11-30 07:09 -0500
          Re: arranging items in a array with a sorted pointer-list James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-11-30 10:02 -0500
    Re: arranging items in a array with a sorted pointer-list Bonita Montero <Bonita.Montero@gmail.com> - 2020-11-29 13:52 +0100
  Re: arranging items in a array with a sorted pointer-list Kaz Kylheku <563-365-8930@kylheku.com> - 2020-11-29 18:34 +0000
    Re: arranging items in a array with a sorted pointer-list Juha Nieminen <nospam@thanks.invalid> - 2020-11-30 09:10 +0000

csiph-web