RE: Character Sets

["Robert C. Leif" <rleif@rleif.com>]

Since XML documents specify a character set, it would be useful to have
the equivalent in Ada. The common meaning of character refers to what
one sees on a screen or paper. If one only considers position, then
Latin-1 and Latin-9 are identical. 
I might note that I do not see how with Ada 95 one could directly create
a bounded string or unbounded string of wide characters?
Bob Leif

-----Original Message-----
From: comp.lang.ada-admin@ada.eu.org
[mailto:comp.lang.ada-admin@ada.eu.org] On Behalf Of Stephen Leake
Sent: Monday, December 02, 2002 10:29 AM
To: comp.lang.ada@ada.eu.org
Subject: Re: Character Sets

"Robert C. Leif" <rleif@rleif.com> writes:

> Christoph Grein responded to my inquiry by stating that, "
> Latin_9.Euro_Sign is a name for a character. The same character in
> Latin_1 has a different name, it is the Currency_Sign." "So why do
> you expect this character not to be in the set only because you use
> a different name for it?" The Euro_Sign and the Currency_Sign have a
> different representation according to The ISO 8859 Alphabet Soup
> http://czyborra.com/charsets/iso8859.html
> ------------------------------------------------ GNAT Latin_9
> (ISO-8859-15)includes the following: -- Summary of Changes from
> Latin-1 => Latin-9 --
> ------------------------------------------------
> 
>    --   164     Currency                => Euro_Sign
>    --   166     Broken_Bar              => UC_S_Caron
>    --   168     Diaeresis               => LC_S_Caron
>    --   180     Acute                   => UC_Z_Caron
>    --   184     Cedilla                 => LC_Z_Caron
>    --   188     Fraction_One_Quarter    => UC_Ligature_OE
>    --   189     Fraction_One_Half       => LC_Ligature_OE
>    --   190     Fraction_Three_Quarters => UC_Y_Diaeresis

Hmm. This says to me:

"In the Latin-1 character set, the character with internal value 164
is called 'Currency'. In the Latin-9 character set, the character with
internal value 164 is called 'Euro_Sign'".

Presumably, elsewhere in the Latin-1 and Latin-9 standards, they
specify the "glyph" used to display those characters on a screen or
paper, and the glyph for character 164 is different between Latin-1
and Latin-9.

> Since these are changes, they should not be the same character.

By "same character", we (and Ada) mean "same internal value", ie
"164". However, I suspect you mean "same glyph", in which case they
are not the "same character"; they do not have the same glyph.

> Below are the results of an extension of my original program that
> now tests the characters of Latin_9 from character number 164
> through 190 and prints them out. 

What results would you like from this program?

> I understand that choice of the Windows font will change their
> representation.

Yes, because the choice of font determines the glyph.

> anyone interested, I have put my program at the end of this note. I
> suspect that the best solution would be to introduce UniCode,

I'm not clear what the "problem" is, so I can't tell if this is a
"solution". 

-- 
-- Stephe