Re: Nicest UTF - string case mapping vs. UTF-8/32

From: Markus Scherer (
Date: Fri Dec 03 2004 - 14:07:23 CST

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    I feel the need to correct one misperception:

    Lars Kristan wrote:
    > 4.1 - UTF-32 is probably very useful for certain string operations.
    > Changing case for example. You can do it in-place, like you could with
    > ASCII. Perhaps it can even be done in UTF-8, I am not sure. But even if
    > it is possible today, it is definitely not guaranteed that it will
    > always remain so, so one shouldn't rely on it.

    Wrong even for UTF-32. Sharp s (U+00DF) uppercases to two characters, "SS". Other examples of case
    mapping expansion and contraction are in SpecialCasing.txt (one of the UCD files).

    For UTF-8, there are also _simple_ (1:1) case mappings that change the length (e.g., long s [017F]
    to S) while sharp s to SS happens to not change the UTF-8 string length...


    PS: I wrote UTN #12 :-)

    Opinions expressed here may not reflect my company's positions unless otherwise noted.

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