udp实现客户端服务端通信代码

以下是UDP实现客户端和服务端通信的基本代码，其中客户端发送一个字符串到服务端，服务端接收到字符串并返回一个响应，客户端再次接收到响应并输出到控制台。

服务端代码：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <netinet/in.h>

#define PORT 8888

int main() {
    int server_fd, client_fd;
    struct sockaddr_in server_addr, client_addr;

    // 创建socket
    if ((server_fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
        perror("socket");
        exit(EXIT_FAILURE);
    }

    // 绑定地址
    memset(&server_addr, 0, sizeof(server_addr));
    server_addr.sin_family = AF_INET;
    server_addr.sin_addr.s_addr = htonl(INADDR_ANY);
    server_addr.sin_port = htons(PORT);
    if (bind(server_fd, (struct sockaddr *)&server_addr, sizeof(server_addr)) < 0) {
        perror("bind");
        exit(EXIT_FAILURE);
    }

    // 接收数据
    char buffer[1024];
    int client_len;
    while (1) {
        memset(buffer, 0, sizeof(buffer));
        client_len = sizeof(client_addr);
        if (recvfrom(server_fd, buffer, sizeof(buffer), 0, (struct sockaddr *)&client_addr, &client_len) < 0) {
            perror("recvfrom");
            exit(EXIT_FAILURE);
        }
        printf("Received message from client: %s\n", buffer);

        // 发送响应
        if (sendto(server_fd, "Hello, client!", 14, 0, (struct sockaddr *)&client_addr, client_len) < 0) {
            perror("sendto");
            exit(EXIT_FAILURE);
        }
    }

    return 0;
}

客户端代码：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#define PORT 8888

int main(int argc, char *argv[]) {
    if (argc < 2) {
        printf("Usage: %s <server_ip>\n", argv[0]);
        return 0;
    }

    int client_fd;
    struct sockaddr_in server_addr;

    // 创建socket
    if ((client_fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
        perror("socket");
        exit(EXIT_FAILURE);
    }

    // 发送数据
    memset(&server_addr, 0, sizeof(server_addr));
    server_addr.sin_family = AF_INET;
    server_addr.sin_addr.s_addr = inet_addr(argv[1]);
    server_addr.sin_port = htons(PORT);
    if (sendto(client_fd, "Hello, server!", 14, 0, (struct sockaddr *)&server_addr, sizeof(server_addr)) < 0) {
        perror("sendto");
        exit(EXIT_FAILURE);
    }

    // 接收响应
    char buffer[1024];
    int server_len;
    memset(buffer, 0, sizeof(buffer));
    server_len = sizeof(server_addr);
    if (recvfrom(client_fd, buffer, sizeof(buffer), 0, (struct sockaddr *)&server_addr, &server_len) < 0) {
        perror("recvfrom");
        exit(EXIT_FAILURE);
    }
    printf("Received message from server: %s\n", buffer);

    return 0;
}

需要注意的是，在实际应用中，需要根据具体的需求和场景进行代码的修改和完善。