diff --git a/day3/qq2/qq3.c b/day3/qq2/qq3.c
new file mode 100644
index 0000000..33a48df
--- /dev/null
+++ b/day3/qq2/qq3.c
@@ -0,0 +1,123 @@
+// 群聊(组播-多播)
+#include <stdio.h>
+#include <arpa/inet.h>
+#include <netinet/in.h>
+#include <sys/socket.h>
+#include <unistd.h>
+#include <string.h>
+#include <stdlib.h>
+#include <pthread.h>
+#include <sys/types.h>
+
+/*
+* ./a.out port
+*/
+
+void *recv_task(void *arg);
+void *send_task(void *arg);
+
+int bind_port;
+char groupip[16] = "";
+
+int main(int argc, char const *argv[])
+{
+    if (argc < 3)
+    {
+        printf("usage: %s port groupip\n", argv[0]);
+        return -1;
+    }
+
+    bind_port = atoi(argv[1]);
+    strcpy(groupip, argv[2]); // 多播组ip
+
+    int sock_fd = socket(AF_INET, SOCK_DGRAM, 0);
+    if (sock_fd < 0)
+    {
+        perror("socket");
+        return EXIT_FAILURE; // 1
+    }
+
+    // 绑定端口
+    struct sockaddr_in bind_addr;
+    memset(&bind_addr, 0, sizeof(bind_addr));
+    bind_addr.sin_family = AF_INET;
+    bind_addr.sin_port = htons(bind_port);
+    bind_addr.sin_addr.s_addr = htonl(INADDR_ANY);
+    bind(sock_fd, (struct sockaddr *)&bind_addr, sizeof(bind_addr)); // 绑定文件描述符和地址端口
+
+    // 设置 socket 选项为多播(组号从命令行获取)
+    struct ip_mreq group_mreq;                            // 组消息请求结构体对象
+    group_mreq.imr_multiaddr.s_addr = inet_addr(groupip); // 添加多播组的ip
+    group_mreq.imr_interface.s_addr = htonl(INADDR_ANY);  // 当前主机的所有 ip 地址加入多播组中
+
+    int ret = setsockopt(sock_fd, IPPROTO_IP, IP_ADD_MEMBERSHIP, &group_mreq, sizeof(group_mreq));
+    if (ret != 0)
+    {
+        perror("setsockopt");
+    }
+
+    pthread_t tid1, tid2;
+    pthread_create(&tid1, NULL, recv_task, &sock_fd);
+    pthread_create(&tid2, NULL, send_task, &sock_fd);
+
+    pthread_join(tid2, NULL);
+    pthread_cancel(tid1);
+    pthread_join(tid1, NULL);
+
+    printf("---over---\n");
+    close(sock_fd);
+
+    return 0;
+}
+
+void *recv_task(void *arg)
+{
+    int sock_fd = *((int *)arg);
+
+    while (1)
+    {
+        struct sockaddr_in data_addr;
+        socklen_t data_addr_len = sizeof(data_addr);
+        bzero(&data_addr, data_addr_len);
+
+        char buf[128] = "";
+
+        ssize_t recv_len = recvfrom(sock_fd, buf, 128, 0, (struct sockaddr *)&data_addr, &data_addr_len);
+        if (recv_len > 0)
+        {
+            char ip[16] = "";
+            inet_ntop(AF_INET, &data_addr.sin_addr.s_addr, ip, 16);
+            printf("%s(%d): %s\n", ip, ntohs(data_addr.sin_port), buf);
+        }
+    }
+}
+
+void *send_task(void *arg)
+{
+    int sock_fd = *((int *)arg);
+
+    while (1)
+    {
+        char buf[128] = "";
+        if (fgets(buf, 128, stdin) != NULL)
+        {
+            buf[strlen(buf) - 1] = 0;
+
+            struct sockaddr_in addr;
+            bzero(&addr, sizeof(addr));
+            addr.sin_family = AF_INET;
+            addr.sin_port = htons(bind_port);
+            addr.sin_addr.s_addr = inet_addr(groupip); // 一定是多播地址
+
+            sendto(sock_fd, buf, strlen(buf) + 1, 0, (struct sockaddr *)&addr, sizeof(addr));
+            if (strncmp(buf, "bye", 3) == 0)
+            {
+                break;
+            }
+            if (strncmp(buf, "clear", 5) == 0)
+            {
+                system("clear");
+            }
+        }
+    }
+}
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