• 方法1，windows平臺能拿到所有網絡卡IP，linux只能獲得 "127.0.0.1"

int m_get_localIP(char** ipList, int num)
{
	int i = 0;
	const char* ip = NULL;
	struct hostent* h = NULL;
	char hostname[128] = {0};
	
	if(gethostname(hostname, sizeof(hostname)) != 0 || (h = gethostbyname(hostname)) == NULL)
	{
		return -1;
	}
	//get the ip address if it has multiple
	for(i = 0;i < num && h->h_addr_list[i];i++)
	{
		ip = inet_ntoa(*(struct in_addr*)h->h_addr_list[i]);
		if(strcmp(ip, "127.0.0.1") != 0)
		{
			strcpy(ipList[i++], ip);
		}
	}
	return i;
}
 

• 方法2，linux平臺可以拿到所有網絡卡IP，windows沒有定義SIOCGIFCONF 和SIOCGIFADDR

int m_get_localIP(char** ipList, int num)
{
	int fd = -1;
	int i = -1, ret = 0;
	const char* ip = NULL;
	struct ifconf ifc = {0}; ///if.h
	struct ifreq* buf = NULL;

	if((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0)
	{
		return -1;
	}
	ifc.ifc_len = num * sizeof(struct ifreq);
	buf = (struct ifreq*)malloc(ifc.ifc_len);
	ifc.ifc_buf = (caddr_t)buf;
	if(ioctl(fd, SIOCGIFCONF, (char*)&ifc) == 0) //ioctl.h
	{
		i = 0;
		ret = ifc.ifc_len / sizeof(struct ifreq);
		while(ret-- > 0 && i < num)
		{
			if((ioctl(fd, SIOCGIFADDR, (char*)&buf[ret])) == 0)
			{
				ip = (inet_ntoa(((struct sockaddr_in*)(&buf[ret].ifr_addr))->sin_addr));//types
				if(strcmp(ip, "127.0.0.1") != 0)
				{
					strcpy(ipList[i++], ip);
				}
			}
		}
	}
	close(fd);
	free(buf);
	return i;
}
 

• 方法三，各平臺通用，但是隻能獲得系統分配的網絡卡IP，不能拿到所有網絡卡IP

int m_get_localIP(char** ipList, int num)
{
    int fd = -1;  
    int i = -1, ret = 0;  
    const char* ip = NULL;  
    struct sockaddr_in addr = {0};  
  
    if((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0)  
    {  
        return -1;  
    }  
    memset(&addr, 0, sizeof(addr));  
    addr.sin_family = AF_INET;  
    addr.sin_addr.s_addr = inet_addr("8.8.8.8");  
    addr.sin_port = htons(80);  
    ret = sizeof(addr);  
    ret = connect(fd, (struct sockaddr*)&addr, ret);  
    i = 0;  
    ret = sizeof(addr);  
    if(getsockname(fd, (struct sockaddr*)&addr, (int*)&ret) == 0)  
    {  
        fprintf(stdout, "ip=%s\n", inet_ntoa(addr.sin_addr));  
    }  
    close(fd);  
    return i;  
}