一、server 端

1. 创建udp::socket，用于收发数据
   1）需要创建一个io_context对象，初始化socket对象
   2）创建一个udp::endpoint对象，指定协议版本（v4，v6）和端口号，初始化socket对象

2. 执行收发动作，socket.receive_from和socket.send_to
   1）收发都需要一个asio::buffer缓存。
   2）receive_from可以获取到client的endpoint，也可以用这个对象给client发送数据（send_to）

二、client 端

1. 创建一个udp::socket对象，用于收发数据。
2. 使用socket对象收发数据，socket.send_to和receive_from
   1）创建一个udp::endpoint对象，指定server端地址、端口。

#include <iostream>
#include <thread>
#include <boost/asio.hpp>using namespace std;
using namespace boost;
using namespace boost::asio;
using asio::ip::udp;void server_func() {io_context io;udp::socket server_socket(io, udp::endpoint(udp::v4(), 22333));int count = 1;while(true) {char buf[128] = {0};udp::endpoint client_endpoint;server_socket.receive_from(asio::buffer(buf), client_endpoint);printf("server -> [%d]: %s\n", count++, buf);cout << "server -> client info: " << client_endpoint.address() << ":" << client_endpoint.port() << endl;server_socket.send_to(asio::buffer("received from server"), client_endpoint);}
}void client_func() {io_context io;udp::socket client_socket(io, udp::v4());udp::endpoint server_endpoint(ip::address::from_string("127.0.0.1"), 22333);while(true) {char buf[128] = {0};cout << "client -> input:\n";cin >> buf;client_socket.send_to(asio::buffer(buf), server_endpoint);//        cout << "client -> get feedback from server: " << server_endpoint.address() << ":" << server_endpoint.port() << endl;
//        bzero(buf, 128);client_socket.receive_from(asio::buffer(buf), server_endpoint);
//        cout << "client -> " << buf << endl;}
}int main() {jthread server(server_func);cout << "start server\n";jthread client(client_func);cout << "start client\n";return 0;
}