[Info-vax] 8-bit characters

[Craig A. Berry]

On 11/11/21 10:21 AM, Arne Vajhøj wrote:
> On 11/10/2021 11:48 PM, Lawrence D’Oliveiro wrote:
>> On Thursday, November 11, 2021 at 3:33:33 PM UTC+13, Arne Vajhøj wrote:
>>> The biggest problems with UTF-8 is that the byte length is not
>>> necessarily the character length ...
>>
>> That would be true of any Unicode encoding, even UCS-4.
> 
> No.
> 
> It is a practical problem in UTF-8 as everything not in ASCII is more 
> than 1 byte.
> 
> It is a theoretical problem in UTF-16 because there are defined unicode
> code points that become more than 2 bytes (they are just extremely
> rare).
> 
> It is not a problem for UTF-32 as everything is 4 bytes.

Back when it was called UCS-4, I think that was true.  But as far as I
know, all the ones with UTF in the name are varying width.  I think
there are a couple of emojis that take more than 4 bytes and would need
two UTF-32 chunks to represent a single character. But even if the
encoding is not varying width, the number of characters displayed might
not match the number of code points because of things like combining
characters.