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From: Keith Thompson <Keith.S.Thompson+u@gmail.com>
Newsgroups: comp.lang.c
Subject: Re: Small challenge: sort names
Date: Wed, 08 Apr 2026 17:27:37 -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;
>>   }

I wouldn't, but it's a matter of taste.

> Personally, I prefer to properly identify integer constants
> with the appropriate type annotation.  I always explicitly
> check against NULL rather than using !ptr, for example. I
> never use an unadorned integer for a character constant,
> rather using either 'c' for printables, the legal escapes
> (e.g. \n) and for any non-printable, the appropriate
> octal escape.

I'd probably use 0 rather than 0u for an initial value of a size_t
object.  0u is probably going to have to be converted anyway (unless
size_t happens to be unsigned int).  I don't mind relying on the
implicit conversion in `size_t count = 0;`.

But for `*str != 0`, I prefer `*str != '\0'` -- not because it
matters to the compiler (it doesn't), but because I find it easier
to read.  I like the visible reminder that it's a character value.

> 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.

It does.  A constant 0 is always a null pointer constant.
Converting an NPC to a pointer type, implicitly or explicitly,
always yields a null pointer value, regardless of how null pointer
values happen to be represented.  But I still prefer using NULL
(or nullptr in C23 or C++) when I want a null pointer value.

-- 
Keith Thompson (The_Other_Keith) Keith.S.Thompson+u@gmail.com
void Void(void) { Void(); } /* The recursive call of the void */