[boost] [iostreams]howto replace ostream buffer?

How can one use iostreams::filtering_streambuf to replace the std::basic_streambuf used by cout. I've tried the code in 1st attachment; however, that code produces the output in 2nd attachment. The desired output is shown in 3ird attachment. How should the code be modified to get the desired output? TIA. -regards, Larry Hello World! is_complete=1 3ird Hello! Hello World! is_complete=1 2ND HELLO! 3ird Hello!