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From: Tim Rentsch <tr.17687@z991.linuxsc.com>
Newsgroups: comp.lang.c
Subject: Re: Small challenge: sort names
Date: Wed, 08 Apr 2026 22:14:25 -0700
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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.