客户端

#include <iostream>

#include <stdio.h>
#include <WinSock2.h>
#pragma comment(lib, "ws2_32.lib")  //加载 ws2_32.dll
#pragma warning(disable : 4996)

#define BUF_SIZE 100

int main() {
    //初始化DLL
    WSADATA wsaData;
    WSAStartup(MAKEWORD(2, 2), &wsaData);

    //创建套接字
    SOCKET sock = socket(PF_INET, SOCK_DGRAM, 0);

    //服务器地址信息
    sockaddr_in servAddr;
    memset(&servAddr, 0, sizeof(servAddr));  //每个字节都用0填充
    servAddr.sin_family = PF_INET;
    // servAddr.sin_addr.s_addr = inet_addr("127.0.0.1");
    servAddr.sin_addr.s_addr = inet_addr("192.168.8.4");
    servAddr.sin_port = htons(65535);

    //不断获取用户输入并发送给服务器，然后接受服务器数据
    sockaddr fromAddr;
    int addrLen = sizeof(fromAddr);
    while (1)
    {
        char buff[BUF_SIZE] = { 0 };
        printf("Input a string: ");
        gets_s(buff);
        sendto(sock, buff, strlen(buff), 0, (struct sockaddr*)&servAddr, sizeof(servAddr));
    }
    closesocket(sock);
    WSACleanup();
    return 0;
}

服务端

//1.创建udp通信socket
  int udp_socket_fd=socket(AF_INET,SOCK_DGRAM,0);
  int port=65535;
  if(udp_socket_fd<0)
    {
      perror("create socket fail\n");
      //return -1;
    }
  //2.设置UDP的地址并绑定
  struct sockaddr_in local_addr ={0};
  local_addr.sin_family=AF_INET;  //使用IPv4协议
  local_addr.sin_port=htons(port);   //网络通信都使用大端格式
  local_addr.sin_addr.s_addr=INADDR_ANY;  //让系统检测本地网卡，自动绑定本地IP

  int ret = bind(udp_socket_fd,(struct sockaddr*)&local_addr,sizeof(local_addr));
  if(ret<0)
    {
      perror("bind fail:");
      close(udp_socket_fd);
      //return -1;
    }
  else
    {
      printf("recv ready!!!\n");
    }
  struct sockaddr_in  src_addr = {0};  //用来存放对方(信息的发送方)的IP地址信息
  int len = sizeof(src_addr); //地址信息的大小
  char buf[1024] = {0};//消息缓冲区

  //循环接受客户端发送过来的数据
  while(1)
    {
      ret = recvfrom(udp_socket_fd, buf, sizeof(buf), 0, (struct sockaddr *)&src_addr, &len);
      if(ret == -1)
      {
        break;
      }
      printf("[%s:%d]",inet_ntoa(src_addr.sin_addr),ntohs(src_addr.sin_port));//打印消息发送方的ip与端口号
      printf("buf=%s\n",buf);
      if(strcmp(buf, "exit") == 0)
      {
      break;
      }
      memset(buf, 0, sizeof(buf));//清空存留消息
    }