I am trying to make an asynchronised server in visual studio and I use

boost::asio::async_read(m_socket, boost::asio::buffer(m_buffer), 
                        boost::bind(&tcp_connection::handle_read, shared_from_this(),
                                    boost::asio::placeholders::error));

to get the buffer to be put in m_buffer

boost::array<char, 256> m_buffer;

but how do I get the size of this thing, m_buffer?

size() didn't work, end() didn't work.. Any help would be fantastic. Thanks in advance.