Hi, I've looked at iostream library for the first time in a long while and had couple surprises waiting for me right at doorstep (I am boost 1.33.1 under vc 7.1 io=boost::iostream). 1) io::array_source( "Hello World!" ) doesn't compile 2) io::array_source( std::string( "Hello World!" ) ) doesn't compile 3) can't seem to find toupper and similar filters as part of the library 4) Given line filter like this: struct toupper_line_filter : io::line_filter { virtual std::string do_filter( const std::string& line ) { std::string result; result.reserve( line.size() ); for( std::string::size_type i = 0, size = line.size(); i < size; ++i ) result.push_back( std::toupper((unsigned char)line[i]) ); return result; } }; Following code seems to produce an error std::string result; io::filtering_ostream out; out.push( toupper_line_filter() ); out.push( io::back_inserter(result) ); out << "Hello World!"; BOOST_CHECK_EQUAL( result, "HELLO WORLD!\n" ); 5) my next attempt was to add flush before check - still the same result std::string result; io::filtering_ostream out; out.push( toupper_line_filter() ); out.push( io::back_inserter(result) ); out << "Hello World!"; out.flush() BOOST_CHECK_EQUAL( result, "HELLO WORLD!\n" ); It appears flush had no effect whatsoever. After long battle i found that reset seems to do the trick. But what if I do not want to destroy stream 6) out.sync() doesn't seems to compile, in spite of what docs say 7) stringstream can't be used at sink: std::stringstream buffer; io::filtering_ostream out; out.push( buffer ); fails to compile 8) library seems to have it's own mind about when to invoke my filter. Can I enforce to be called manually? Thanks, Gennadiy