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Re: Simple(?) Unicode questions

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Tim Rentsch <tr.17687@z991.linuxsc.com> writes:
> Keith Thompson <Keith.S.Thompson+u@gmail.com> writes:
>> Tim Rentsch <tr.17687@z991.linuxsc.com> writes:
>>> Lew Pitcher <lew.pitcher@digitalfreehold.ca> writes:
>>>> On Wed, 13 Dec 2023 11:05:45 +0800, spender wrote:
>>>>> printf("%c",ch), the ch must <0xFF, <255
>>>>
>>>> Not quite.
>>>> 1) ch /must/ represent an integer value.
>>>
>>> More specifically, it must have a type that is or promotes
>>> to int, or a type that is or promotes to unsigned int, with
>>> a value that is in the common range of int and unsigned int.
>>
>> Not quite.  "If no l length modifier is present, the int argument
>> is converted to an unsigned char, and the resulting character is
>> written."  For example printf("%c", -193) is equivalent to
>> printf("%c", 63), which assuming an ASCII-based character set will
>> print '?'.
>
> The rule for arguments to printf() is the same as the rule for
> accessing variadic arguments using va_arg().  That has always
> been true, although not expressed clearly in early versions of
> the C standard.  Fortunately that shortcoming is addressed in
> the upcoming C23 (is it still not yet ratified?):  in N3096,
> paragraph 9 in section 7.23.6.1 says in part
>
>     fprintf shall behave as if it uses va_arg with a type
>     argument naming the type resulting from applying the
>     default argument promotions to the type corresponding
>     to the conversion specification [...]
>
> and the rule for va_arg (in 7.16.1.1 p2) says in part 
>
>     one type is a signed integer type, the other type is
>     the corresponding unsigned integer type, and the value
>     is representable in both types
>
> So supplying an unsigned int argument is okay, provided of
> course the value is in the range of values of signed int.

Re-reading what you wrote, I think I misunderstood your intent (and I
think what you wrote was ambiguous).

"%c" specifies an int argument.

You wrote:

    More specifically, it must have a type that is or promotes to int,
    or a type that is or promotes to unsigned int, with a value that is
    in the common range of int and unsigned int.

I read that as:

    More specifically,
    (it must have a type that is or promotes to int, or a type that is
    or promotes to unsigned int),
    with a value that is in the common range of int and unsigned int.

which would incorrectly imply that a negative int value is not allowed.

It's now clear to me that you meant was:

    More specifically,
    (it must have a type that is or promotes to int),
    or
    (a type that is or promotes to unsigned int, with a value that is in
    the common range of int and unsigned int).

I agree with that.

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

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Re: Simple(?) Unicode questions Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2023-12-13 14:56 +0000
  Re: Simple(?) Unicode questions Tim Rentsch <tr.17687@z991.linuxsc.com> - 2023-12-25 02:03 -0800
    Re: Simple(?) Unicode questions Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2023-12-25 14:43 -0800
      Re: Simple(?) Unicode questions Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-01-20 09:33 -0800
        Re: Simple(?) Unicode questions Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-01-20 14:19 -0800
          Re: Simple(?) Unicode questions Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-01-24 20:38 -0800

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