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Re: Simple(?) Unicode questions

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Keith Thompson <Keith.S.Thompson+u@gmail.com> writes:

> 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.

Right.  Sorry for the confusion.

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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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