C 에서 한글 처리

UNICODE UNDER LINUX
Under GNU/Linux, the C type wchar_t is a signed 32-bit integer type.
Its values are always interpreted by the C library as UCS code values
(in all locales), a convention that is signaled by the GNU C library to
applications by defining the constant __STDC_ISO_10646__ as specified
in the ISO C 99 standard.

UCS/Unicode can be used just like ASCII in input/output streams, termi?
nal communication, plaintext files, filenames, and environment vari?
ables in the ASCII compatible UTF-8 multi-byte encoding. To signal the
use of UTF-8 as the character encoding to all applications, a suitable
locale has to be selected via environment variables (e.g.,
"LANG=en_GB.UTF-8").

The nl_langinfo(CODESET) function returns the name of the selected
encoding. Library functions such as wctomb(3) and mbsrtowcs(3) can be
used to transform the internal wchar_t characters and strings into the
system character encoding and back and wcwidth(3) tells, how many posi?
tions (0?2) the cursor is advanced by the output of a character.

Under Linux, in general only the BMP at implementation level 1 should
be used at the moment. Up to two combining characters per base charac?
ter for certain scripts (in particular Thai) are also supported by some
UTF-8 terminal emulators and ISO 10646 fonts (level 2), but in general
precomposed characters should be preferred where available (Unicode
calls this Normalization Form C).