Re: When does toUpperCase(ch) == ch ?

From: Mark Davis (
Date: Tue Oct 10 2000 - 04:19:14 EDT

In general, you can't depend on any of the following:

toUppercase(x) == x iff Cat(x) == Lu
toTitlecase(x) == x iff Cat(x) == Lt
toLowercase(x) == x iff Cat(x) == Ll

There are counterexamples to these, even using the simple 1-1 mappings. Take
a look at the casing charts, at

And of course they are definitely not true once you add the complete
mappings from SpecialCasing.txt (which you have to have for correct casing),
and include the locale-dependent mappings (such as for Turkey). Look at

----- Original Message -----
From: "John O'Conner" <>
To: "Unicode List" <>
Sent: Monday, October 09, 2000 23:40
Subject: When does toUpperCase(ch) == ch ?

> I intend on testing this with a few perl scripts later using the db, but
> thought I'd pose the question to see if anyone has a quick answer:
> Is it true that if a character's general category is neither Ll nor Lt,
> then the uppercase character is simply the character itself?
> Regards,
> John O'Conner

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