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Re: Corrupted C99 _Bool?

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"das...@gmail.com" <dashley@gmail.com> writes:
> C99 indicates that a _Bool is an unsigned integer type.  When a
> variable of a type other than _Bool is assigned to a _Bool, C99
> specifies that the _Bool receives the value of 0 if the variable was
> 0, or 1 otherwise.
>
> But what does C99 say about a _Bool that is corrupted to a value other
> than 0 or 1 (perhaps through a pointer error in another part of the
> program)?  Will this corrupted _Bool still function correctly?
>
> For example:
>
> _Bool a = true;
> _Bool b; /* Assume b is corrupted to "2" somehow */
>
> if (a && b)
> {
>    /* Would the compiler be able to use a bitwise */
>    /* AND above, because it assumes all _Bools */
>    /* must be 0 or 1, so that if (1 && 2) becomes */
>    /* if (1 & 2) and evaluates false? */
> }
>
> Thanks for any clarification.

I'm reasonably sure that anything that would cause a _Bool object to
have a value other than 0 or 1, or at least anything that tried to
access such an object's value, would have undefined behavior.

Using bitwise AND for the code above is one of the infinitely many
things a compiler could do.

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

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Corrupted C99 _Bool? "das...@gmail.com" <dashley@gmail.com> - 2023-07-11 17:32 -0700
  Re: Corrupted C99 _Bool? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2023-07-11 18:51 -0700
    Re: Corrupted C99 _Bool? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2023-07-11 19:13 -0700
    Re: Corrupted C99 _Bool? James Kuyper <jameskuyper@alumni.caltech.edu> - 2023-07-12 02:47 -0400
    Re: Corrupted C99 _Bool? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2023-07-20 21:25 -0700
      Re: Corrupted C99 _Bool? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2023-07-21 01:58 -0700
        Re: Corrupted C99 _Bool? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2023-07-21 14:22 -0700
  Re: Corrupted C99 _Bool? David Brown <david.brown@hesbynett.no> - 2023-07-12 09:31 +0200
  Re: Corrupted C99 _Bool? Opus <ifonly@youknew.org> - 2023-07-12 22:10 +0200
    Re: Corrupted C99 _Bool? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2023-07-12 14:21 -0700
      Re: Corrupted C99 _Bool? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2023-07-20 22:17 -0700
    Re: Corrupted C99 _Bool? James Kuyper <jameskuyper@alumni.caltech.edu> - 2023-07-12 18:44 -0400
      Re: Corrupted C99 _Bool? "das...@gmail.com" <dashley@gmail.com> - 2023-07-12 16:41 -0700
        Re: Corrupted C99 _Bool? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2023-07-13 01:17 +0100
        Re: Corrupted C99 _Bool? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2023-07-12 17:28 -0700
        Re: Corrupted C99 _Bool? David Brown <david.brown@hesbynett.no> - 2023-07-13 11:27 +0200
          Re: Corrupted C99 _Bool? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2023-07-13 15:18 -0700
            Re: Corrupted C99 _Bool? David Brown <david.brown@hesbynett.no> - 2023-07-14 09:07 +0200
            Re: Corrupted C99 _Bool? "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2023-07-14 00:53 -0700
    Re: Corrupted C99 _Bool? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2023-07-20 22:09 -0700

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