Garbage value in Boost::Array using with Boost::Asio

Client is writing like this

    std::string line;
    std::cin>>line;      
    boost::asio::write(socket, boost::asio::buffer(line));

Server is Reading like this

void reader(){   
           socket_.async_read_some(boost::asio::buffer(buf),
           boost::bind(&tcp_connection::handle_read,shared_from_this()));     
  }
void handle_read()
    {
          std::cout.write(buf.data(),1024);
          std::cout<<"\n";
    }
  tcp::socket socket_;
  boost::array<char, 1024> buf;

Now when i am writing a line "hello how are you" from client , it is just printing "hello" and then garbage values
here is the output which server is showing:

helloA0�B��B�����a�Pa�!0�B�b����uB�`�#K|BP�b��D4B���Bb�Pa���e��e�����pc�!0�Be���xB�`�#KcBe�:7B�����e��e���  

how can I remove this garbage values and get complete message/line from client