Re: Man page pre & post operators error

["Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com>]

Hello Rick,

(Im reflecting more.)

On 9/25/19 9:42 PM, Michael Kerrisk (man-pages) wrote:
> Hello Rick,
> 
> On 9/25/19 5:23 PM, Rick Stanley wrote:
>> Hello again!
>>
>> In an effort to bring the current manpage for the C operator table up
>> to the current official Standard, I went back and compared the current
>> manpage operator table against the C99, C11, and C17(18) Draft
>> Standards documents.  I do not have access to the Official ISO C
>> Standards documents.
>>
>> I have attached a PDF to document my interpretation of the Standards
>> against the current `man operator` manpage
>>
>> In addition to the pre & postfix ++ & -- operators, I have found one
>> additional change & three additions to the table.  Because of these
>> appearing in 6.5.x, and A.2.1, I assume they should be included in the
>> operator table.
>>
>> The current table consists of 15 levels of precedence, C99 adds one new
>> level and C11 adds one more.
>>
>> (type) cast operator change
>>
>> In the current table, the cast operator is listed on level 2 of 15
>> levels, along with other operators.  In C99 this operator has been
>> demoted to a new level inserted between level 2 & 3 of the current
>> level, expanding the table to 16 levels of precedence.  I assume the
>> associativity is also "right to left", as is level 2.

How do you deduce that this changed between C89/90 and c99?
I'm not so convinced now that '(type) cast' changed in precedence.

>> _Generic operator/keyword addition
>>
>> This new operator/keyword was added in C11.  A new top level was
>> created and the remainder of the table has been demoted by one level.

But, is it really an operator? How do you deduce that?

>> default operator/keyword addition
>>
>> This too has been added to the new top level in C11
> 
> But, 'default' is not an operator as far as I can tell?
> (It is part of the '_Generic' construct, not an operator
> in its own right.)
> 
>> _Alignof operator/keyword addition

This seems clearly correct to me, and I find other sources
that agree on this.

My general problem is that I find no other sources
that confirm your interpretation of the standard that _Generic
is a new operator at a new level and that '(type) cast' has
changed in precedence.

Thanks,

Michael


-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/