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From: Michael S <already5chosen@yahoo.com>
Newsgroups: comp.lang.c
Subject: Re: question about nullptr
Date: Tue, 9 Jul 2024 11:00:19 +0300
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On Tue, 9 Jul 2024 02:49:49 -0000 (UTC)
Kaz Kylheku <643-408-1753@kylheku.com> wrote:

> On 2024-07-08, Michael S <already5chosen@yahoo.com> wrote:
> > On Sun, 07 Jul 2024 15:17:34 -0700
> > Keith Thompson <Keith.S.Thompson+u@gmail.com> wrote:
> >  
> >> 
> >> I just about always use NULL, not 0, when I want a null pointer
> >> constant.  Similarly, I use '\0', not 0, when I want a null
> >> character, 0.0 when I want a floating-point zero, and false when I
> >> want a Boolean zero.  I just like being explicit.
> >>   
> >
> > Pointer: I very rarely use NULL.
> > Character: I never use '\0'.
> > Floating point: I never use 0.0.  
> 
> Never say never!
> 
>   printf("%f\n", 0);   // undefined behavior.
>   printf("%f\n", 0.0); // correct
>

Yes, but that's extremely rare that I want constant (except string
literal) as variable argument to printf().

> If you're #define-ing a floating-point constant that has
> no fractional part, you should put that .0 there.
>

I am trying hard to avoid #define-ing floating-point constants.
In rare cases where it is not avoidable, most often the constant does
have fractional part. I am not sure what I would prefer when I can't
avoid #define-ing and the constant has no fractional part. Will I write
something like '#define ANSWER ((double)42)' or (42.0) ?
It depends on the mood of the minute.

> Someone's going to pass your constant as a variadic argument,
> where it doesn't convert to floating-point.
> 
> Also:
> 
>   1/3   -> 0
>   1/3.0 -> 0.33333...
> 
> If you're #define-ing a floating point constant that has
> no fractional part, and don't include the .0, and the
> programmer uses it as a division denominator thinking that
> it's a floating-point quantity, oops!
>