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Re: C precedence - relative comparisons before equality operators

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On 9/5/21 4:19 PM, Kenny McCormack wrote:
> In article <sh2vvh$oir$1@dont-email.me>,
> James Harris  <james.harris.1@gmail.com> wrote:
>> According to
>>
>>   https://en.cppreference.com/w/c/language/operator_precedence
>>
>> and other references C applies relative comparisons (<, <=, >=, >) 
>> before equality comparisons (==, !=) rather than giving them all the 
>> same priority.
>>
>> Anyone know why the precedences were designed that way?
>>
>> Are there certain idioms in which that arrangement is useful?
> 
> I think it makes sense.  If I see:
> 
>     if (a < b == c < d)
> 
> I would expect it to mean:
> 
>     if ((a < b) == (c < d))
> 
> That's got to be more useful than:
> 
>     if ((a < (b == c)) < d)
> 

I think that is probably about as good of an arguement as any will find.

Since the grammer doesn't easily support what some later langagues did
to make a < b < c to mean (a < b) && (b < c) which can be handy being
able to say something like a < b == b < c at least lets you test if 3
numbers are in sequence without parenthesis.

Also, it puts less operators at any give level of the grammer which
might be useful. You end up with more levels of grammer, but each one is
simpler.

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C precedence - relative comparisons before equality operators James Harris <james.harris.1@gmail.com> - 2021-09-05 18:49 +0100
  Re: C precedence - relative comparisons before equality operators Siri Cruise <chine.bleu@yahoo.com> - 2021-09-05 13:11 -0700
  Re: C precedence - relative comparisons before equality operators Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-09-05 21:12 +0100
    Re: C precedence - relative comparisons before equality operators David Brown <david.brown@hesbynett.no> - 2021-09-06 09:09 +0200
  Re: C precedence - relative comparisons before equality operators gazelle@shell.xmission.com (Kenny McCormack) - 2021-09-05 20:19 +0000
    Re: C precedence - relative comparisons before equality operators Richard Damon <Richard@Damon-Family.org> - 2021-09-05 17:52 -0400
      Re: C precedence - relative comparisons before equality operators Bart <bc@freeuk.com> - 2021-09-06 00:09 +0100
        Re: C precedence - relative comparisons before equality operators David Brown <david.brown@hesbynett.no> - 2021-09-06 09:15 +0200
          Re: C precedence - relative comparisons before equality operators Bart <bc@freeuk.com> - 2021-09-06 11:10 +0100
            Re: C precedence - relative comparisons before equality operators David Brown <david.brown@hesbynett.no> - 2021-09-06 13:01 +0200
              Re: C precedence - relative comparisons before equality operators Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2021-09-06 04:20 -0700
    Re: C precedence - relative comparisons before equality operators John Bode <jfbode1029@gmail.com> - 2021-09-07 09:27 -0500
      Re: C precedence - relative comparisons before equality operators Bart <bc@freeuk.com> - 2021-09-08 00:20 +0100
        Re: C precedence - relative comparisons before equality operators John Bode <jfbode1029@gmail.com> - 2021-09-08 14:18 -0500
  Re: C precedence - relative comparisons before equality operators Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-09-06 02:01 +0100
    Re: C precedence - relative comparisons before equality operators James Harris <james.harris.1@gmail.com> - 2021-09-06 09:39 +0100
      Re: C precedence - relative comparisons before equality operators Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-09-06 10:46 +0100
        Re: C precedence - relative comparisons before equality operators Richard Damon <Richard@Damon-Family.org> - 2021-09-06 10:09 -0400
          Re: C precedence - relative comparisons before equality operators Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-09-06 16:05 +0100
  Re: C precedence - relative comparisons before equality operators James Harris <james.harris.1@gmail.com> - 2021-09-06 09:27 +0100
    Re: C precedence - relative comparisons before equality operators James Harris <james.harris.1@gmail.com> - 2021-09-06 12:18 +0100
      Re: C precedence - relative comparisons before equality operators David Brown <david.brown@hesbynett.no> - 2021-09-06 13:44 +0200
        Re: C precedence - relative comparisons before equality operators James Harris <james.harris.1@gmail.com> - 2021-09-06 13:38 +0100
          Re: C precedence - relative comparisons before equality operators David Brown <david.brown@hesbynett.no> - 2021-09-06 18:12 +0200
        Re: C precedence - relative comparisons before equality operators tth <tth@none.invalid> - 2021-09-06 18:20 +0200
          Re: C precedence - relative comparisons before equality operators David Brown <david.brown@hesbynett.no> - 2021-09-06 23:40 +0200
      Re: C precedence - relative comparisons before equality operators Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-09-06 17:20 -0700
    Re: C precedence - relative comparisons before equality operators Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-09-06 13:44 +0100
    Re: C precedence - relative comparisons before equality operators Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-09-06 17:23 -0700
  Re: C precedence - relative comparisons before equality operators James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-09-06 23:07 -0400

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