服务端程序：server.c
1 #include2 #include 3 #include 4 #include 5 #include 6 #include 7 8 9 10 11 #define PORT 1234512 13 int main()14 {15 struct sockaddr_in server_addr, client_addr;16 char msg[1024];17 int len;18 static count = 1;19 int fd = socket(AF_INET, SOCK_DGRAM, 0);20 bzero(&server_addr, sizeof(struct sockaddr_in));21 22 server_addr.sin_family = AF_INET;23 server_addr.sin_port = htons(PORT);24 server_addr.sin_addr.s_addr = inet_addr("127.0.0.1");25 26 bind(fd, (struct sockaddr*)&server_addr, sizeof(struct sockaddr_in));27 28 socklen_t addr_len;29 while(1)30 {31 bzero(msg, sizeof(msg));32 addr_len = sizeof(client_addr);33 len = recvfrom(fd, msg, sizeof(msg), 0, (struct sockaddr*)&client_addr, &addr_len);//百度百科直接搜34 printf("%d: ", len);35 printf("msg from: %s\n", inet_ntoa(client_addr.sin_addr));36 printf("msg: %s\n", msg);37 sendto(fd, msg, len, 0, (struct sockaddr*)&client_addr, addr_len);//百度百科直接搜38 39 }40 41 return 0;42 43 }
客户端程序：client.c
1 #include2 #include 3 #include 4 #include 5 #include 6 #include 7 8 9 10 11 #define PORT 12345 12 #define IP "127.0.0.1"13 int main()14 {15 struct sockaddr_in server_addr;16 char msg[1024];17 int len;18 int fd = socket(AF_INET, SOCK_DGRAM, 0); //创建socket，注意udp创建的是数据包套接字，SOCK_DGRAM19 if(fd < 0)20 {21 printf("socket error\n");22 }23 bzero(&server_addr, sizeof(struct sockaddr_in)); //相当于memset(&server_addr, 0, sizeof(struct sockaddr_in));24 25 //指定服务端的端口和ip26 server_addr.sin_family = AF_INET; 27 server_addr.sin_port = htons(PORT);28 29 inet_pton(AF_INET, "127.0.0.1", &server_addr.sin_addr);30 31 32 socklen_t addr_len;33 int ret;34 int n;35 while(1)36 {37 //int n = read(STDIN_FILENO, msg, sizeof(msg));38 fgets(msg, 1024, stdin); //用户输入字符串，fgets会读入字符'\n'39 printf(" msg: %s", msg);40 //发送到server端41 ret = sendto(fd, msg, strlen(msg), 0, (struct sockaddr*)&server_addr, sizeof(server_addr));42 printf("ret: %d\n", ret);43 //接收从服务端收到的字符串44 n = recvfrom(fd, msg, sizeof(msg), 0, NULL, NULL);45 printf("n=%d\n", n);46 msg[n]='\0';// 收到的字符串后面没有'\0'，无法printf输出，所以在字符串后添加'\0'47 printf("%s", msg);48 printf("__________________________________\n");49 50 }51 52 return 0;53 54 }