Hi. I've implemented output stream using boost.iostreams library. It requires call to flush in order to actually write data to sink. But I want to flush data to sink automatically after I write any object with operator<<. struct stream_sink : public boost::iostreams::sink { stream_sink(std::ostream & strm) : strm_(strm) {} std::streamsize write(const char * s, std::streamsize n) { if (strm_.write(s, n)) return n; else throw std::runtime_error("error"); } private: std::ostream & strm_; }; std::stringstream s; boost::iostreams::stream strm(s); strm << "abc"; strm.flush(); std::cout << "String: '" << s.str() << "'" << std::endl; This test outputs "String: 'abc'" but if you comment strm.flush() then it outputs "String: ''". I want my stream to work like the stringstream does (it does not require call to flush). std::stringstream strm; strm << "abc"; std::string s; strm >> s; std::cout << "String: '" << s << "'" << std::endl; It outputs "String: 'abc'". I need it to create stream which can be used to convert wide char data (wchar_t *) to multibyte (char *). It can be used this way: // wcstombsstream is wostream and istream // "utf-8" is multibyte encoding wcstombsstream strm("utf-8"); strm << L"abc"; std::string s; strm >> s; This code does not work at the moment because it requires to call strm.flush() before reading from stream. Thus I need some auto flush facility :-) Thank you for any help, Roman Perepelitsa.