The tm structure contains the following members
int tm_sec; /* seconds, 0-60 */
int tm_min; /* minutes, 0-59 */
int tm_hour; /* hours, 0-23 */
int tm_mday; /* day of the month, 1-31 */
int tm_mon; /* months since Jan, 0-11 */
int tm_year; /* years from 1900 */
int tm_wday; /* days since Sunday, 0-6 */
int tm_yday; /* days since Jan 1, 0-365 */
int tm_isdst /* Daylight Saving Time indicator */
tm_isdst is positive during daylight saving time, zero if it not, and
negative if there is no information available.