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);    //得到对方的套接字

udp::socket socket(io_service);

socket.open(udp::v4());    //打开自己的UDP套接字

boost::array send_buf = {{0}};

socket.send_to(boost::asio::buffer(send_buf),reciver_endpoint);    //向对方的套接字端口发送报文

boost::array recv_buf;

udp::endpoint sender_endpoint;

size_t len = socket.receive_from(boost::asio::buffer(recv_buf), sender_endpoint);    //接收报文，将来者套接字保存在sender_endpoint中

std::cout.write(recv_buf.data(), len);    //打印收到的内容

}

catch(std::exception &e)

{

std::cerr << e.what() << std::endl;

}

return 0;

}

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

==============================================================================================

源码：q.cpp

#include

#include

#include

#include

#include

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));    //创建一个套接字在UDP端口13上监听

for(; ; )

{

boost::array recv_buf;

udp::endpoint remote_endpoint;

boost::system::error_code error;

socket.receive_from(boost::asio::buffer(recv_buf), remote_endpoint, 0, error);   //由接受到的数据报中得到时间请求者的地址，保存在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);     //向请求者发送时间信息

}

}

catch(std::exception &e)

{

std::cerr << e.what() << std::endl;

}

return 0;

}

编译：g++ q.cpp -lboost_system -lpthread -o q.out

==============================================================================================

#include

#include

#include

#include

#include

#include

#include

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))    //初始化端口为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 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));    //发送操作完成后执行handle_send句柄

start_receive();

}

}

void handle_send(boost::shared_ptr /*message*/,

const boost::system::error_code& /*error*/,

std::size_t /*bytes_transferred*/)

{

}

udp::socket socket_;

udp::endpoint remote_endpoint_;

boost::array 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;

}