c/c++常用代码--udp多播

#include <stdio.h>
#include <stdlib.h>
#include <windows.h>
#include <winsock.h>

#pragma comment(lib, "ws2_32.lib")

#define close closesocket

#undef IP_ADD_MEMBERSHIP
#define IP_ADD_MEMBERSHIP 12

int main(void)
{
    WSADATA wsa={};
    WSAStartup(MAKEWORD(,),&wsa);

    SOCKET fd;
    SOCKADDR_IN localif;    

    fd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
    ) {
        perror("socket");
        ;
    }

    localif.sin_family = AF_INET;
    localif.sin_port   = htons();
    localif.sin_addr.s_addr = htonl(INADDR_ANY);
    ) {
        perror("bind");
        ;
    }

    ;
    if (setsockopt(fd, IPPROTO_IP, IP_MULTICAST_TTL, (char *)&ttl, sizeof(ttl)) == SOCKET_ERROR) {
        printf("setsockopt IP_MULTICAST_TTL %d", WSAGetLastError());
        ;
    }

    struct ip_mreq mreq;
    memset(&mreq, , sizeof(mreq));

    mreq.imr_interface.s_addr = inet_addr("192.168.1.145");
    mreq.imr_multiaddr.s_addr = inet_addr("234.0.0.1"); //234.5.6.7

    ) {
        printf("setsockopt IP_ADD_MEMBERSHIP %d", WSAGetLastError());
        ;
    }

    while (true) {
        ] = {};
        );
        ) {
            perror("recv");
            ;
        }
        buf[n] = ;
        printf("%s", buf);
    }

    ) {
        printf("setsockopt IP_DROP_MEMBERSHIP %d", WSAGetLastError());
        ;
    }

    WSACleanup();

    ;
}