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From: Keith Thompson <Keith.S.Thompson+u@gmail.com>
Newsgroups: comp.lang.c
Subject: Re: Representation of _Bool
Date: Mon, 24 May 2021 13:15:11 -0700
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Ben Bacarisse <ben.usenet@bsb.me.uk> writes:
> Keith Thompson <Keith.S.Thompson+u@gmail.com> writes:
>> Conclusions:
>>
>> sizeof (_Bool) >= 1.  It may be greater than 1, but that would
>> be weird.  If sizeof (_Bool) > 1, then it must have padding bits.
>
> I don't understand how you draw that last conclusion.

[answered elsethread]

> <cut>
>> Here's a small program that attempts to explore how an implementation
>> represents objects of type _Bool:
>>
>> #include <stdio.h>
>> #include <limits.h>
>>
>> union U {
>>     _Bool b;
>>     unsigned char rep;
>> };
>
> When doing this kind of thing, my preference is to write
>
>   union U {
>       _Bool b;
>       unsigned char rep[sizeof (_Bool)];
>   };
>
> even when it's very unlikely that the size will be > 1.  It makes the
> purpose so very clear.

Good point.

-- 
Keith Thompson (The_Other_Keith) Keith.S.Thompson+u@gmail.com
Working, but not speaking, for Philips Healthcare
void Void(void) { Void(); } /* The recursive call of the void */