time.h

time.h 定义了两个宏：NULLCLOCKS_PER_SEC包含四个类型：size_tclock_ttime_tstruct tm和九个函数：clock_t clock(void);double difftime(time_t time1, time_t time0);time_t mktime(struct tm *timeptr);time_t time(time_t *timer);char *asctime(const struct tm *timeptr);char *ctime(const time_t *timer);struct tm *gmtime(const time_t *timer);struct tm *localtime(const time_t *timer);size_t strftime(char * restrict s, size_t maxsize, const char * restrict format, const struct tm * restrict timeptr);