u_normalize transforms Unicode text into an equivalent composed or decomposed form, allowing for easier sorting and searching of text

u_normalize transforms Unicode text into an equivalent composed or decomposed form, allowing for easier sorting and searching of text. u_normalize supports the standard normalization forms described in Unicode Technical Report #15.

Characters with accents or other adornments can be encoded in several different ways in Unicode. For example, take the character "�" (A-acute). In Unicode, this can be encoded as a single character (the "composed" form):

00C1    LATIN CAPITAL LETTER A WITH ACUTE

or as two separate characters (the "decomposed" form):

0041    LATIN CAPITAL LETTER A
0301    COMBINING ACUTE ACCENT

To a user of your program, however, both of these sequences should be treated as the same "user-level" character "�". When you are searching or comparing text, you must ensure that these two sequences are treated equivalently. In addition, you must handle characters with more than one accent. Sometimes the order of a character's combining accents is significant, while in other cases accent sequences in different orders are really equivalent.

Similarly, the string "ffi" can be encoded as three separate letters:

0066    LATIN SMALL LETTER F
0066    LATIN SMALL LETTER F
0069    LATIN SMALL LETTER I

or as the single character

FB03    LATIN SMALL LIGATURE FFI

The ffi ligature is not a distinct semantic character, and strictly speaking it shouldn't be in Unicode at all, but it was included for compatibility with existing character sets that already provided it. The Unicode standard identifies such characters by giving them "compatibility" decompositions into the corresponding semantic characters. When sorting and searching, you will often want to use these mappings.

u_normalize helps solve these problems by transforming text into the canonical composed and decomposed forms as shown in the first example above. In addition, you can have it perform compatibility decompositions so that you can treat compatibility characters the same as their equivalents. Finally, u_normalize rearranges accents into the proper canonical order, so that you do not have to worry about accent rearrangement on your own.

u_normalize adds one optional behavior, {@link #UCOL_IGNORE_HANGUL}, that differs from the standard Unicode Normalization Forms.

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