I have just discovered the incredible boost and regex++ libraries but I have encountered some difficulties... I read that the japanese special encoding is handled in regex++, specially using wide char wchar characters. In the regex++ faq, it is presented the system of class , ex. [[:space]], in order to define a set of characters with a same property. I have been looking for a kind of [[:Japanese characters]] class. Actually I have a text with a lot of strange characters and japanese one ( Hiragana, katakan, Kanji everything..!) and I want to find these japanese sentence in order to translate them and replace in the text. I need hence a way in order to identify a japanese sentence . A kind of function const bool isJap( const wchar ) const would be fine. So if somebody has any idea or a some links, I would appreciate it! Thanks! ~~~~~~~~~~~~~~~~~~~~~~~ Two options: 1) You can hack the traits class used by boost.regex: Create your own traits class that inherits from boost::regex_traits and which implements the following member functions: uint32_t lookup_classname(const char_type* first, const char_type* last)const; bool is_class(char_type c, uint32_t f)const; The first transforms your character-class name into a constant, the latter checks to see if a character is a member of that class. Choose a value for your constant that isn't already in use by regex_traits. Finally use reg_expression<wchar_t, your_traits_class<wchar_t> > rather than boost::wregex. 2) Just use a character range - most Japanese characters are confined to a specific character range (I forget what it is, but the info is publicly available via the Unicode std). John.