获取当天00:00:00时间值秒数

 //获取今天00:00:00的UNIX时间值

    time_t cur_time;

    cur_time = time(NULL); //

    struct tm *time_tm;

    time_tm = localtime(&cur_time);

    time_tm->tm_hour=0;

    time_tm->tm_min=0;

    time_tm->tm_sec=0;

    //printf("%d\n",(unsigned int)mktime(time_tm));

    uint32_t today_begin = mktime(time_tm);