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Re: Small challenge: sort names

From Tim Rentsch <tr.17687@z991.linuxsc.com>
Newsgroups comp.lang.c
Subject Re: Small challenge: sort names
Date 2026-04-08 22:14 -0700
Organization A noiseless patient Spider
Message-ID <86h5pkww9a.fsf@linuxsc.com> (permalink)
References (2 earlier) <10r5vh2$3mo17$2@dont-email.me> <10r64uq$3pf3r$1@dont-email.me> <YpzBR.6$rGx6.1@fx24.iad> <20260409001030.000006c9@yahoo.com> <bDBBR.139$Np7d.78@fx15.iad>

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scott@slp53.sl.home (Scott Lurndal) writes:

> Michael S <already5chosen@yahoo.com> writes:
>
>> On Wed, 08 Apr 2026 21:04:56 GMT
>> scott@slp53.sl.home (Scott Lurndal) wrote:
>>
>>> Bart <bc@freeuk.com> writes:
>>>
>>>> On 08/04/2026 17:25, DFS wrote:
>>>>
>>>>> On 4/8/2026 4:22 AM, Janis Papanagnou wrote:
>>>>
>>>> //count characters in a string
>>>> int countchr(char *str, char chr)
>>>> {int
>>>> c=0,cnt=0;while(str[c]!='\0'){if(str[c]==chr){cnt++;}c++;}return
>>>> cnt;}
>>>>
>>>> I couldn't quite figure out what it did;  counting characters in a
>>>> string (like the comment says)?  But strlen will do that.  Then I
>>>> noticed that the extra 'chr' parameter, so maybe it stops at 'chr'.
>>>>
>>>> But when I tried running it as countchr("ABCDEFGH", 'E'), it
>>>> returned 1, not 4 or 5.
>>>>
>>>> So I refactored it like this:
>>>>
>>>>   int countchr(char *str, char chr) {
>>>>       int c=0, cnt=0;
>>>>       while (str[c]!='\0') {
>>>>           if (str[c] == chr) cnt++;
>>>>           c++;
>>>>       }
>>>>       return cnt;
>>>>    }
>>>
>>> Idiomatically, I might have written
>>>
>>>    size_t
>>>    countchar(const char *str, char match)
>>>    {
>>>        size_t count = 0u;
>>>        for(; *str != '\0'; str++) count += (*str == match);
>>>        return count;
>>>    }
>>
>> I'd change it to
>>
>>   size_t
>>   countchar(const char *str, char match)
>>   {
>>       size_t count = 0;
>>       for(; *str != 0; str++) count += (*str == match);
>>       return count;
>>   }
>
> Personally, I prefer to properly identify integer constants
> with the appropriate type annotation.

A dangerous habit if followed out of habit.  For example:

    size_t ones = -1;   // makes 'ones' be all one bits
    size_t ones = -1u;  // oops!  can be 32 ones rather than 64

> I always explicitly check against NULL rather than using !ptr,
> for example.

I consider the treatment of null pointers and the way if(), for(),
while(), etc, work to be a pleasing symmetry and an elegant
simplifying principle of the C language.  Pointers are a special
kind of multi-valued booleans.  Writing this

    char *p = ...;
    if( p != NULL ) ...

is just as repugnant as this

    _Bool b = ...;
    if( b != false ) ...

> Perhaps some of this is pedantic.   I worked with a system
> where the null pointer constant was not the value zero, so
> I'm aware that !ptr may not actually do the right thing in
> such cases.

The semantics of !ptr has been codified to mean 1 for null pointers
since the original C standard.  Heck, even during the 1970s when C
allowed assigning integers directly to pointers, K&R said that
assigning 0 to a pointer produces a pointer guaranteed to be
different than a pointer to any object.  Any C implementation where
!ptr does the wrong thing should be avoided like the plague.

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Thread

Small challenge: sort names DFS <nospam@dfs.com> - 2026-04-07 23:14 -0400
  Re: Small challenge: sort names Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-04-08 10:22 +0200
    Re: Small challenge: sort names DFS <nospam@dfs.com> - 2026-04-08 12:25 -0400
      Re: Small challenge: sort names Bart <bc@freeuk.com> - 2026-04-08 18:57 +0100
        Re: Small challenge: sort names scott@slp53.sl.home (Scott Lurndal) - 2026-04-08 21:04 +0000
          Re: Small challenge: sort names Michael S <already5chosen@yahoo.com> - 2026-04-09 00:10 +0300
            Re: Small challenge: sort names scott@slp53.sl.home (Scott Lurndal) - 2026-04-08 23:35 +0000
              Re: Small challenge: sort names Michael S <already5chosen@yahoo.com> - 2026-04-09 02:59 +0300
                Re: Small challenge: sort names James Kuyper <jameskuyper@alumni.caltech.edu> - 2026-04-09 06:29 -0400
                Re: Small challenge: sort names cross@spitfire.i.gajendra.net (Dan Cross) - 2026-04-09 15:15 +0000
                Re: Small challenge: sort names Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-04-11 08:49 -0700
                Re: Small challenge: sort names cross@spitfire.i.gajendra.net (Dan Cross) - 2026-04-11 19:59 +0000
                Re: Small challenge: sort names Bonita Montero <Bonita.Montero@gmail.com> - 2026-04-16 18:50 +0200
                Re: Small challenge: sort names cross@spitfire.i.gajendra.net (Dan Cross) - 2026-04-16 19:54 +0000
                Re: Small challenge: sort names Bonita Montero <Bonita.Montero@gmail.com> - 2026-04-17 16:22 +0200
              Re: Small challenge: sort names Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-04-08 17:27 -0700
              Re: Small challenge: sort names Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-04-08 22:14 -0700
                Re: Small challenge: sort names Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-04-09 02:19 -0700
                Re: Small challenge: sort names scott@slp53.sl.home (Scott Lurndal) - 2026-04-09 15:06 +0000
                Re: Small challenge: sort names Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-04-12 06:35 -0700
                Re: Small challenge: sort names scott@slp53.sl.home (Scott Lurndal) - 2026-04-12 14:51 +0000
                Re: Small challenge: sort names Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-04-13 06:31 -0700
                Re: Small challenge: sort names Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-04-12 06:48 -0700
                Re: Small challenge: sort names Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-04-12 16:15 -0700
                Re: Small challenge: sort names Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-04-25 13:31 -0700
          Re: Small challenge: sort names Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-04-11 08:44 +0200
        Re: Small challenge: sort names DFS <nospam@dfs.com> - 2026-04-08 17:13 -0400
          Re: Small challenge: sort names Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-04-11 08:59 +0200
            Re: Small challenge: sort names Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-04-11 09:34 +0200
      Re: Small challenge: sort names Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-04-11 08:31 +0200
    Re: Small challenge: sort names BGB <cr88192@gmail.com> - 2026-04-12 13:08 -0500
    What is the point of anything? (Was: Small challenge: sort names) gazelle@shell.xmission.com (Kenny McCormack) - 2026-04-17 20:44 +0000
  Re: Small challenge: sort names Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-04-08 18:46 -0700
  Re: Small challenge: sort names Sort <Sort@invalid.invalid> - 2026-04-11 19:15 +0100
  Re: Small challenge: sort names Bonita Montero <Bonita.Montero@gmail.com> - 2026-04-16 18:24 +0200
    Re: Small challenge: sort names Bart <bc@freeuk.com> - 2026-04-16 18:38 +0100
      Re: Small challenge: sort names Bonita Montero <Bonita.Montero@gmail.com> - 2026-04-16 19:43 +0200
    Re: Small challenge: sort names Bart <bc@freeuk.com> - 2026-04-18 11:22 +0100
      Re: Small challenge: sort names Bonita Montero <Bonita.Montero@gmail.com> - 2026-04-18 17:48 +0200
        Re: Small challenge: sort names Bonita Montero <Bonita.Montero@gmail.com> - 2026-04-19 08:44 +0200
    Re: Small challenge: sort names DFS <nospam@dfs.com> - 2026-04-22 05:33 -0400
      Re: Small challenge: sort names Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-04-22 03:16 -0700
        Re: Small challenge: sort names DFS <nospam@dfs.com> - 2026-04-22 07:35 -0400
          Re: Small challenge: sort names Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-04-23 08:11 -0700
            Re: Small challenge: sort names Bonita Montero <Bonita.Montero@gmail.com> - 2026-04-23 20:14 +0200
              Re: Small challenge: sort names gazelle@shell.xmission.com (Kenny McCormack) - 2026-04-23 18:30 +0000
        Re: Small challenge: sort names gazelle@shell.xmission.com (Kenny McCormack) - 2026-04-23 17:19 +0000
      Re: Small challenge: sort names Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-04-22 14:11 +0200
        Re: Small challenge: sort names James Kuyper <jameskuyper@alumni.caltech.edu> - 2026-04-22 21:27 -0400
          [OT][meta] Gender (was Re: Small challenge: sort names) Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-04-23 15:51 +0200
            Re: [OT][meta] Gender (was Re: Small challenge: sort names) scott@slp53.sl.home (Scott Lurndal) - 2026-04-23 14:45 +0000
              Re: [OT][meta] Gender (was Re: Small challenge: sort names) Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-04-23 17:03 +0200
              Re: [OT][meta] Gender (was Re: Small challenge: sort names) DFS <nospam@dfs.com> - 2026-04-23 20:31 -0400
                Re: [OT][meta] Gender (was Re: Small challenge: sort names) Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-04-23 18:43 -0700
                Re: [OT][meta] Gender (was Re: Small challenge: sort names) gazelle@shell.xmission.com (Kenny McCormack) - 2026-04-24 16:58 +0000
                Re: [OT][meta] Gender (was Re: Small challenge: sort names) Jan van den Broek <balglaas@dds.nl> - 2026-04-24 06:57 +0000
                Re: [OT][meta] Gender (was Re: Small challenge: sort names) Bonita Montero <Bonita.Montero@gmail.com> - 2026-04-24 10:10 +0200
                Re: [OT][meta] Gender (was Re: Small challenge: sort names) David Brown <david.brown@hesbynett.no> - 2026-04-24 12:52 +0200
            Re: [OT][meta] Gender (was Re: Small challenge: sort names) Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-04-23 16:36 -0700
              Re: [OT][meta] Gender (was Re: Small challenge: sort names) Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-04-24 03:01 +0200
                Re: [OT][meta] Gender (was Re: Small challenge: sort names) Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-04-23 18:50 -0700
                Re: [OT][meta] Gender (was Re: Small challenge: sort names) "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-04-24 20:35 -0700
            Re: [OT][meta] Gender (was Re: Small challenge: sort names) Michael S <already5chosen@yahoo.com> - 2026-04-24 14:20 +0300
              Re: [OT][meta] Gender (was Re: Small challenge: sort names) Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-04-24 14:32 +0200
      Re: Small challenge: sort names Bonita Montero <Bonita.Montero@gmail.com> - 2026-04-23 20:10 +0200
        Re: Small challenge: sort names DFS <nospam@dfs.com> - 2026-04-25 10:26 -0400
  Re: Small challenge: sort names Rosario19 <Ros@invalid.invalid> - 2026-04-18 11:16 +0200
    Re: Small challenge: sort names DFS <nospam@dfs.com> - 2026-04-18 08:11 -0400
      Re: Small challenge: sort names Bart <bc@freeuk.com> - 2026-04-18 14:03 +0100
    Re: Small challenge: sort names Rosario19 <Ros@invalid.invalid> - 2026-04-20 21:20 +0200
      Re: Small challenge: sort names DFS <nospam@dfs.com> - 2026-04-20 16:43 -0400
        Re: Small challenge: sort names Rosario19 <Ros@invalid.invalid> - 2026-04-21 05:09 +0200
          Re: Small challenge: sort names DFS <nospam@dfs.com> - 2026-04-21 08:46 -0400
            Re: Small challenge: sort names Bart <bc@freeuk.com> - 2026-04-21 16:08 +0100
              Re: Small challenge: sort names DFS <nospam@dfs.com> - 2026-04-21 11:33 -0400
                Re: Small challenge: sort names Bart <bc@freeuk.com> - 2026-04-21 18:25 +0100
                Re: Small challenge: sort names scott@slp53.sl.home (Scott Lurndal) - 2026-04-21 17:38 +0000
                Re: Small challenge: sort names Michael S <already5chosen@yahoo.com> - 2026-04-21 20:50 +0300
                Re: Small challenge: sort names scott@slp53.sl.home (Scott Lurndal) - 2026-04-21 18:22 +0000
                Re: Small challenge: sort names Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-04-22 03:48 +0200
                Re: Small challenge: sort names David Brown <david.brown@hesbynett.no> - 2026-04-22 09:18 +0200
                Re: Small challenge: sort names Michael S <already5chosen@yahoo.com> - 2026-04-22 13:22 +0300
                Re: Small challenge: sort names David Brown <david.brown@hesbynett.no> - 2026-04-22 12:38 +0200
                Re: Small challenge: sort names Michael S <already5chosen@yahoo.com> - 2026-04-22 13:58 +0300
                Re: Small challenge: sort names David Brown <david.brown@hesbynett.no> - 2026-04-22 13:13 +0200
                Re: Small challenge: sort names Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-04-22 14:53 +0200
                Re: Small challenge: sort names DFS <nospam@dfs.com> - 2026-04-21 16:31 -0400
                Re: Small challenge: sort names Bart <bc@freeuk.com> - 2026-04-21 23:04 +0100
      Re: Small challenge: sort names Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-04-20 14:16 -0700
        An audience of one (Was: Small challenge: sort names) gazelle@shell.xmission.com (Kenny McCormack) - 2026-04-21 13:00 +0000
          Re: An audience of one (Was: Small challenge: sort names) "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-04-21 12:21 -0700
    Re: Small challenge: sort names Rosario19 <Ros@invalid.invalid> - 2026-04-21 05:00 +0200
      Re: Small challenge: sort names Rosario19 <Ros@invalid.invalid> - 2026-04-21 05:06 +0200
  Re: Small challenge: sort names gggggggggggunit <gunitinug@50cent.com> - 2026-04-18 10:19 +0000
    [OT] Shell approach to Re: Small challenge: sort names Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-04-19 09:35 +0200
      Re: [OT] Shell approach to Re: Small challenge: sort names gazelle@shell.xmission.com (Kenny McCormack) - 2026-04-19 14:18 +0000
        Re: [OT] Shell approach to Re: Small challenge: sort names cross@spitfire.i.gajendra.net (Dan Cross) - 2026-04-19 19:32 +0000
          Re: [OT] Shell approach to Re: Small challenge: sort names Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-04-22 03:34 +0200

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