Hello , I include <boost/regex.hpp> in my program, when compiling I got message: boost/regex/v4/char_regex_traits.hpp:34: error: wrong number of template arguments (1, should be 2). I checked the wrong line in boost/regex/v4/char_regex_traits.hpp .. template <calss charT> class char_regex_traits_i : public regex_traits<charT>{}; template<> class char_regex_traits_i<char> : public regex_traits<char> { public: typedef char char_type; typedef unsigned char uchar_type; typedef unsigned int size_type; typedef regex_traits<char> base_type; }; and then I checked the template regex_traits defined in boost/regex/v4/regex_traits.hpp: template <class charT, class implementationT > struct regex_traits : public implementationT { regex_traits() : implementationT() {} }; It's really a but, do you thinks so? what should the implementationT be for char_regex_traits_i in boost/regex/v4/char_regex_traits.hpp? Who could give some suggession, thanks! -- ------------------------------- Enjoy life! Barco You