Here's the details on struct tm from <time.h>:

Code:
struct tm
    Represents the components of calendar time:

    int tm_sec;
        seconds after the minute
    int tm_min;
        minutes after the hour
    int tm_hour;
        hours since midnight
    int tm_mday;
        day of the month
    int tm_mon;
        months since January
    int tm_year;
        years since 1900
    int tm_wday;
        days since Sunday
    int tm_yday;
        days since January 1
    int tm_isdst;
        Daylight Saving Time flag : is positive if DST is in effect, zero if not in effect, negative if information not known.

    Implementations may change field order and include additional fields.
You could also define your own struct - if you haven't learnt about them yet, you should..