Code snippet to give you the idea

filter_msg_buffer::filter_msg_buffer(const int msglen)

: msg_buffer(msglen)

{

// ... stuff deleted ...

original_streambuf = cout.rdbuf ( (streambuf *) this);

}

// in the destructor, we restore the original streambuf for cout.

filter_msg_buffer::~filter_msg_buffer()

{

cout.rdbuf ( original_streambuf );

}

The streambuf constructor retains the pointer to cout’s old streambuf and registers itself to be the new streambuf.

In the destuctor we reverse the process and restore the original streambuf.