Method encode_header

example/cpp11/chat/chat_message.hpp:79–85

  }

  void encode_header()
  {
    char header[header_length + 1] = "";
    std::snprintf(header, header_length + 1,
        "%4d", static_cast<int>(body_length_));
    std::memcpy(data_, header, header_length);
  }

private:
  char data_[header_length + max_body_length];