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Re: | vs || operator on C99 bool types

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On 6/27/2011 12:21, Matthias Arndt wrote:
> Hello all,
>
> I heard an opinion on the use of the | operator together with C99
> conform bool types (stdbool.h)
>
> My discussion partner stated that
> _Bool a, b;
> ......
> a | b;
>
> should be forbidden and a || b should be used instead.
>

Forbidden?  "... The rank of _Bool shall be less than the rank of all 
other standard integer types. ..."[6.3.1.1p1]  That is a discussion 
which concludes with the definition of "the integer promotions."

Then we have for '|'[6.5.12p3] that the "usual arithmetic conversions" 
are performed, which in this case includes the integer 
promotions[6.3.1.8p1].  So using '_Bool' doesn't appear to be forbidden.

Perhaps your discussion partner believes that the construct "ought to 
be" ("should be" makes me think that something "is already true," given 
some reference) because any non-value bits in a '_Bool' are not very 
useful in a program.

> I personally can't see the difference for true boolean types (which
> would be *implementation* specific, but let's assume an embedded
> compiler with a true bool type that maps to a real bit.)
>
> What does the standard say? Are there opinions on this?
>
> I personally have no true opinion on this, otherwise I wouldn't open
> this up for discussion.

However the value is stored, it undergoes the integer promotions and is 
not longer a '_Bool' by the time it's used in the context you provide, 
as far as I understand it.

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Thread

| vs || operator on C99 bool types Matthias Arndt <marndt@asmsoftware.de> - 2011-06-27 16:21 +0000
  Re: | vs || operator on C99 bool types Shao Miller <sha0.miller@gmail.com> - 2011-06-27 13:38 -0400
  Re: | vs || operator on C99 bool types Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-06-27 21:51 -0400
    Re: | vs || operator on C99 bool types James Waldby <not@valid.invalid> - 2011-06-28 16:16 +0000
      [OT] Genderangement [Was: Re: | vs || operator on C99 bool types] Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-06-28 20:35 -0400
        Re: [OT] Genderangement [Was: Re: | vs || operator on C99 bool types] blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2011-06-29 21:33 +0000
          Re: [OT] Genderangement [Was: Re: | vs || operator on C99 bool types] Michael Press <rubrum@pacbell.net> - 2011-06-30 10:58 -0700
            Re: [OT] Genderangement [Was: Re: | vs || operator on C99 bool types] blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2011-06-30 18:57 +0000
              Re: [OT] Genderangement [Was: Re: | vs || operator on C99 bool types] Michael Press <rubrum@pacbell.net> - 2011-07-01 12:53 -0700
                Re: [OT] Genderangement [Was: Re: | vs || operator on C99 bool types] blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2011-07-02 18:27 +0000
                Re: [OT] Genderangement [Was: Re: | vs || operator on C99 bool types] Michael Press <rubrum@pacbell.net> - 2011-07-03 20:53 -0700
      Re: | vs || operator on C99 bool types Nick Keighley <nick_keighley_nospam@hotmail.com> - 2011-07-03 03:34 -0700
        Re: | vs || operator on C99 bool types James Kuyper <jameskuyper@verizon.net> - 2011-07-03 08:25 -0400
          Re: | vs || operator on C99 bool types gordonb.pbl6v@burditt.org (Gordon Burditt) - 2011-07-03 18:23 -0500
  Re: | vs || operator on C99 bool types James Kuyper <jameskuyper@verizon.net> - 2011-06-28 07:21 -0400
    Re: | vs || operator on C99 bool types James Kuyper <jameskuyper@verizon.net> - 2011-06-28 08:24 -0400
      Re: | vs || operator on C99 bool types Matthias Arndt <marndt@asmsoftware.de> - 2011-06-28 16:11 +0000
  Re: | vs || operator on C99 bool types Tim Rentsch <txr@alumni.caltech.edu> - 2011-06-28 16:37 -0700
    Re: | vs || operator on C99 bool types Nick Keighley <nick_keighley_nospam@hotmail.com> - 2011-07-03 03:41 -0700
      Re: | vs || operator on C99 bool types Tim Rentsch <txr@alumni.caltech.edu> - 2011-07-03 15:02 -0700

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