International Components for Unicode
http://icu-project.org

ICU is a set of C and C++ libraries that provides robust and
full-featured Unicode and locale support. The library provides calendar
support, conversions for many character sets, language sensitive
collation, date and time formatting, support for many locales, message
catalogs and resources, message formatting, normalization, number and
currency formatting, time zone support, transliteration, and word,
line, and sentence breaking, etc.