UDP发送广播信息

发送广播数据 
    SOCKET s = ::socket(AF_INET, SOCK_DGRAM, 0);
    // 有效SO_BROADCAST选项
    BOOL bBroadcast = TRUE;
    ::setsockopt(s, SOL_SOCKET, SO_BROADCAST, (char*)&bBroadcast, sizeof(BOOL));
    // 设置广播地址，这里的广播端口号（电台）是4567
    SOCKADDR_IN bcast;
    bcast.sin_family = AF_INET;
    bcast.sin_addr.s_addr = INADDR_BROADCAST; // ::inet_addr("255.255.255.255");
    bcast.sin_port = htons(4567);
    // 发送广播
    printf(" 开始向4567端口发送广播数据... /n /n");
    char sz[] = "This is just a test. /r/n";
    while(TRUE)
    {
          ::sendto(s, sz, strlen(sz), 0, (sockaddr*)&bcast, sizeof(bcast));
          ::Sleep(5000);
    }