1.同步方式的UDP-daytime客戶端

原始碼：p.cpp #include <iostream> #include <boost/asio.hpp> #include <boost/array.hpp> using boost::asio::ip::udp; int main(int argc, char* argv[]) {  try  {   if(argc != 2){    std::cerr << "Usage: client <host>" <<std::endl;    return 1;   }   boost::asio::io_service io_service;   udp::resolver resolver(io_service);   udp::resolver::query query(udp::v4(), argv[1], "daytime");   udp::endpoint reciver_endpoint = *resolver.resolve(query);    //得到對方的套接字   udp::socket socket(io_service);   socket.open(udp::v4());    //開啟自己的UDP套接字   boost::array<char, 1> send_buf = {{0}};   socket.send_to(boost::asio::buffer(send_buf),reciver_endpoint);    //向對方的套接字埠傳送報文   boost::array<char, 128> recv_buf;   udp::endpoint sender_endpoint;   size_t len = socket.receive_from(boost::asio::buffer(recv_buf), sender_endpoint);    //接收報文，將來者套接字儲存在sender_endpoint中   std::cout.write(recv_buf.data(), len);    //列印收到的內容  }  catch(std::exception &e)  {   std::cerr << e.what() << std::endl;  }  return 0; } 編譯

：g++ p.cpp -lboost_system -lpthread -o p.out ==============================================================================================

2.同步方式的UDP-daytime伺服器

原始碼：q.cpp #include <iostream> #include <string> #include <ctime> #include <boost/asio.hpp> #include <boost/array.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));    //建立一個套接字在UDP埠13上監聽   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);   //由接受到的資料報中得到時間請求者的地址，儲存在remote_endpoint中    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);     //向請求者傳送時間資訊   }  }  catch(std::exception &e)  {   std::cerr << e.what() << std::endl;  }  return 0; } 編譯：g++ q.cpp -lboost_system -lpthread -o q.out ==============================================================================================

3.非同步方式的UDP-daytime伺服器

原始碼：r.cpp #include <ctime> #include <iostream> #include <string> #include <boost/array.hpp> #include <boost/bind.hpp> #include <boost/shared_ptr.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); } class udp_server { public:   udp_server(boost::asio::io_service& io_service)     : socket_(io_service, udp::endpoint(udp::v4(), 13))    //初始化埠為13的UDP套接字   {     start_receive();   } private:   void start_receive()   {     socket_.async_receive_from(         boost::asio::buffer(recv_buffer_), remote_endpoint_,         boost::bind(&udp_server::handle_receive, this,           boost::asio::placeholders::error,           boost::asio::placeholders::bytes_transferred));   }   void handle_receive(const boost::system::error_code& error,       std::size_t /*bytes_transferred*/)   {     if (!error || error == boost::asio::error::message_size)     {       boost::shared_ptr<std::string> message(           new std::string(make_daytime_string()));       socket_.async_send_to(boost::asio::buffer(*message), remote_endpoint_,           boost::bind(&udp_server::handle_send, this, message,             boost::asio::placeholders::error,             boost::asio::placeholders::bytes_transferred));    //傳送操作完成後執行handle_send控制代碼       start_receive();     }   }   void handle_send(boost::shared_ptr<std::string> /*message*/,       const boost::system::error_code& /*error*/,       std::size_t /*bytes_transferred*/)   {   }   udp::socket socket_;   udp::endpoint remote_endpoint_;   boost::array<char, 1> recv_buffer_; }; int main() {   try   {     boost::asio::io_service io_service;     udp_server server(io_service);     io_service.run();   }   catch (std::exception& e)   {     std::cerr << e.what() << std::endl;   }   return 0; } 編譯：g++ r.cpp -lboost_system -lpthread -o r.out