Most declarations of functions from /usr/include/time.h
Linux, SuSE 7.3, gcc -v 2.95.3

/* Time used by the program so far (user time + system time). The result / CLOCKS_PER_SECOND is program time in seconds. */ extern clock_t clock (void); /* Return the current time and put it in *TIMER if TIMER is not NULL. */ extern time_t time (time_t *__timer); /* Return the difference between TIME1 and TIME0. */ extern double difftime (time_t __time1, time_t __time0); /* Return the `time_t' representation of TP and normalize TP. */ extern time_t mktime (struct tm *__tp); /* Format TP into S according to FORMAT. Write no more than MAXSIZE characters and return the number of characters written, or 0 if it would exceed MAXSIZE. */ extern size_t strftime (char *__restrict __s, size_t __maxsize, __const char *__restrict __format, __const struct tm *__restrict __tp); # ifdef __USE_XOPEN /* Parse S according to FORMAT and store binary time information in TP. The return value is a pointer to the first unparsed character in S. */ extern char *strptime (__const char *__restrict __s, __const char *__restrict __fmt, struct tm *__tp); # endif /* Return the `struct tm' representation of *TIMER in Universal Coordinated Time (aka Greenwich Mean Time). */ extern struct tm *gmtime (__const time_t *__timer); /* Return the `struct tm' representation of *TIMER in the local timezone. */ extern struct tm *localtime (__const time_t *__timer); # if defined __USE_POSIX || defined __USE_MISC /* Return the `struct tm' representation of *TIMER in UTC, using *TP to store the result. */ extern struct tm *gmtime_r ( __const time_t *__restrict __timer, struct tm *__restrict __tp); /* Return the `struct tm' representation of *TIMER in local time, using *TP to store the result. */ extern struct tm *localtime_r ( __const time_t *__restrict __timer, struct tm *__restrict __tp); # endif /* POSIX or misc */ /* Return a string of the form "Day Mon dd hh:mm:ss yyyy\n" that is the representation of TP in this format. */ extern char *asctime (__const struct tm *__tp); /* Equivalent to `asctime (localtime (timer))'. */ extern char *ctime (__const time_t *__timer); # if defined __USE_POSIX || defined __USE_MISC /* Reentrant versions of the above functions. */ /* Return in BUF a string of the form "Day Mon dd hh:mm:ss yyyy\n" that is the representation of TP in this format. */ extern char *asctime_r ( __const struct tm *__restrict __tp, char *__restrict __buf); /* Equivalent to `asctime_r (localtime_r (timer, *TMP*), buf)'. */ extern char *ctime_r ( __const time_t *__restrict __timer, char *__restrict __buf); # endif /* POSIX or misc */ # ifdef __USE_POSIX extern char *tzname[2]; /* Set time conversion information from the TZ environment variable. If TZ is not defined, a locale-dependent default is used. */ extern void tzset (void); # endif /* Set the system time to *WHEN. This call is restricted to the superuser. */ extern int stime (__const time_t *__when); /* Nonzero if YEAR is a leap year (every 4 years, except every 100th isn't, and every 400th is). */ # define __isleap(year) \ ((year) % 4 == 0 && \ ((year) % 100 != 0 || (year) % 400 == 0)) # ifdef __USE_MISC /* Miscellaneous functions many Unices inherited from the public domain localtime package. These are included only for compatibility. */ /* Like `mktime', but for TP represents Universal Time, not local time. */ extern time_t timegm (struct tm *__tp); /* Another name for `mktime'. */ extern time_t timelocal (struct tm *__tp); /* Return the number of days in YEAR. */ extern int dysize ( int __year); # endif # ifdef __USE_POSIX199309 /* Pause execution for a number of nanoseconds. */ extern int nanosleep ( __const struct timespec *__requested_time, struct timespec *__remaining); /* Get resolution of clock CLOCK_ID. */ extern int clock_getres (clockid_t __clock_id, struct timespec *__res); /* Get current value of clock CLOCK_ID and store it in TP. */ extern int clock_gettime (clockid_t __clock_id, struct timespec *__tp); /* Set clock CLOCK_ID to value TP. */ extern int clock_settime (clockid_t __clock_id, __const struct timespec *__tp); # ifdef __USE_XOPEN2K /* High-resolution sleep with the specified clock. */ extern int clock_nanosleep (clockid_t __clock_id, int __flags, __const struct timespec *__req, struct timespec *__rem); /* Return clock ID for CPU-time clock. */ extern int clock_getcpuclockid (pid_t __pid, clockid_t *__clock_id); # endif /* Create new per-process timer using CLOCK_ID. */ extern int timer_create (clockid_t __clock_id, struct sigevent *__restrict __evp, timer_t *__restrict __timerid); /* Delete timer TIMERID. */ extern int timer_delete (timer_t __timerid); /* Set timer TIMERID to VALUE, returning old value in OVLAUE. */ extern int timer_settime (timer_t __timerid, int __flags, __const struct itimerspec *__restrict __value, struct itimerspec *__restrict __ovalue); /* Get current value of timer TIMERID and store it in VLAUE. */ extern int timer_gettime (timer_t __timerid, struct itimerspec *__value); /* Get expiration overrun for timer TIMERID. */ extern int timer_getoverrun (timer_t __timerid); # endif extern struct tm *getdate (__const char *__string); extern int getdate_r (__const char *__restrict __string, struct tm *__restrict __resbufp);