Cstandardlibrary（c标准库）

e difference between two moments\rTime_t mktime (struct, TM, *tp)\rConverts the segmented time value to the calendar time value\rChar *asctime (const, struct, TM, *tblock)\rThe date and time of the conversion are ASCII yards\rChar *ctime (const, time_t, *time)\rConverts date and time to strings\rStruct, TM, *gmtime (const, *timer).\rChange the date and time to the Greenwich standard time (GMT)\rStruct, TM, *localtime (const, time_t, *timer)\rChange the date and time to structure\rSize_t strftime (char, *s, size t, Smax, const, char, *fmt,\rconst, struct, TM, *tp)\rAccording to the format requirements of FMT, the date and time\rin *tp are converted to the specified format.