time.h(3HEAD) Headers time.h(3HEAD)NAME
time.h, time - time types
SYNOPSIS
#include <time.h>
DESCRIPTION
The <time.h> header declares the structure tm, which includes the fol‐
lowing members:
int tm_sec /* seconds [0,60] */
int tm_min /* minutes [0,59] */
int tm_hour /* hour [0,23] */
int tm_mday /* day of month [1,31] */
int tm_mon /* month of year [0,11] */
int tm_year /* years since 1900 */
int tm_wday /* day of week [0,6] (Sunday =0) */
int tm_yday /* day of year [0,365] */
int tm_isdst /* daylight savings flag */
The value of tm_isdst is positive if Daylight Saving Time is in effect,
0 if Daylight Saving Time is not in effect, and negative if the infor‐
mation is not available.
The <time.h> header defines the following symbolic names:
NULL
Null pointer constant.
CLOCKS_PER_SEC
A number used to convert the value returned by the clock() function
into seconds. See clock(3C).
CLOCK_PROCESS_CPUTIME_ID
The identifier of the CPU-time clock associated with the process
making a clock() or timer*() function call.
CLOCK_THREAD_CPUTIME_ID
The identifier of the CPU-time clock associated with the thread
making a clock() or timer*() function call.
The <time.h> header declares the timespec structure, which has the fol‐
lowing members:
time_t tv_sec /* seconds */
long tv_nsec /* nanoseconds */
The <time.h> header declares the itimerspec structure, which has the
following members:
struct timespec it_interval /* timer period */
struct timespec it_value /* timer expiration */
The following manifest constants are defined:
CLOCK_REALTIME The identifier of the system-wide realtime
clock.
TIMER_ABSTIME Flag indicating time is absolute. For functions
taking timer objects, this refers to the clock
associated with the timer.
CLOCK_MONOTONIC The identifier for the system-wide monotonic
clock, which is defined as a clock whose value
cannot be set with clock_settime() and that
cannot have backward clock jumps. The maximum
possible clock jump is implementation-defined.
See clock_settime(3RT).
The clock_t, size_t, time_t, clockid_t, and timer_t types are defined
as described in <sys/types.h>. See types.h(3HEAD).
Although the value of CLOCKS_PER_SEC is required to be 1 million on all
standard-conforming systems, it can be variable on other systems, and
it should not be assumed that CLOCKS_PER_SEC is a compile-time con‐
stant.
The <time.h> header provides a declaration for getdate_err.
The following are declared as variables:
extern int daylight;
extern long timezone;
extern char *tzname[];
Inclusion of the <time.h> header can make visible all symbols from the
<signal.h> header.
USAGE
The range [0,60] for tm_sec allows for the occasional leap second.
tm_year is a signed value; therefore, years before 1900 can be repre‐
sented.
To obtain the number of clock ticks per second returned by the times()
function, applications should call sysconf(_SC_CLK_TCK). See times(2)
and sysconf(3C).
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌─────────────────────────────┬─────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│Interface Stability │Standard │
└─────────────────────────────┴─────────────────────────────┘
SEE ALSOtime(2), utime(2), clock(3C), ctime(3C), difftime(3C), getdate(3C),
mktime(3C), strftime(3C), strptime(3C), types.h(3HEAD), clock_set‐
time(3RT), nanosleep(3RT), timer_create(3RT), timer_delete(3RT),
timer_settime(3RT), attributes(5), standards(5)SunOS 5.10 10 Sep 2004 time.h(3HEAD)
