text: //
  // server.cpp
  // ~~~~~~~~~~
  //
  // Copyright (c) 2003-2008 Christopher M. Kohlhoff (chris at kohlhoff dot com)
  //
  // Distributed under the Boost Software License, Version 1.0. (See accompanying
  // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
  //
  
  #include <ctime>
  #include <iostream>
  #include <string>
  #include <boost/array.hpp>
  #include <boost/asio.hpp>
  
  using boost::asio::ip::udp;
  
  std::string make_daytime_string()
  {
    using namespace std; // For time_t, time and ctime;
    time_t now = time(0);
    return ctime(&now);
  }
  
  int main()
  {
    try
    {
      boost::asio::io_service io_service;
  
      udp::socket socket(io_service, udp::endpoint(udp::v4(), 13));
  
      for (;;)
      {
        boost::array<char, 1> recv_buf;
        udp::endpoint remote_endpoint;
        boost::system::error_code error;
        socket.receive_from(boost::asio::buffer(recv_buf),
            remote_endpoint, 0, error);
  
        if (error && error != boost::asio::error::message_size)
          throw boost::system::system_error(error);
  
        std::string message = make_daytime_string();
  
        boost::system::error_code ignored_error;
        socket.send_to(boost::asio::buffer(message),
            remote_endpoint, 0, ignored_error);
      }
    }
    catch (std::exception& e)
    {
      std::cerr << e.what() << std::endl;
    }
  
    return 0;
  }
  