Re: [Boost-users] boost filesystems and case issues

From: Lars Viklund (zao_at_[hidden])
Date: 2008-06-10 11:38:21

On Tue, Jun 10, 2008 at 04:45:21PM +0200, Jens Seidel wrote:
> Didn't know this :-) Now I remember that even for German there exists
> "ß" which has no capitalisation. Some people use "SS" or "SZ" or even
> "ß" for it. Don't know what toupper("ß") returns.
> 
> So converting a string containing "ß" to upper case could result in some
> false negatives too :-)
> Nevertheless I'm sure that just a funny example. In praxis it will not
> cause harm.

Actually, in the newly released Unicode 5.1 standard, there's a
codepoint U+1E9E LATIN CAPITAL LETTER SHARP S, but the default unicode
casing rules converts from 'capital sharp s' down to 'small sharp s',
but an upper casing from 'small sharp s' produces 'SS'. There are
however tailored special cases which may be used that produces the
expected roundtrip.

In general, it's unwise to assume that lower/upper casing is
non-destructive, especially in the Unicode world of today.

-- 
Lars Viklund | zao_at_[hidden] | 070-310 47 07