TIME.H(3HEAD) Headers TIME.H(3HEAD)

time.h, time — time types

#include <time.h>

The <time.h> header declares the structure tm, which includes the following 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 information is not available.

The <time.h> header defines the following symbolic names:

The identifier for the system-wide monotonic clock, which is defined as a clock whose value cannot be set with () and that cannot have backward clock jumps. The maximum possible clock jump is implementation-defined. See clock_settime(3C).
A number used to convert the value returned by the () function into seconds. See clock(3C).
The identifier of the CPU-time clock associated with the process making a clock() or () function call. This clock includes both user and system CPU-time.
The identifier of the system-wide realtime clock.
The identifier of the CPU-time clock associated with the thread making a clock() or timer_*() function call. This clock includes both user and system CPU-time.
The identifier of the CPU-time clock associated with the thread making a clock() or timer_*() function call. This clock only includes user CPU-time.
Null pointer constant.
Flag indicating time is absolute. For functions taking timer objects, this refers to the clock associated with the timer.

The <time.h> header defines the following clock constants which are used with the timespec_get(3C) and timespec_getres(3C) calls. Each one has a CLOCK_* equivalent.

The equivalent of CLOCK_REALTIME.
The equivalent of CLOCK_HIGHRES.
The equivalent of CLOCK_PROCESS_CPUTIME_ID.
The equivalent of CLOCK_THREAD_CPUTIME_ID.
The equivalent of CLOCK_VIRTUAL.

The <time.h> header declares the timespec structure, which has the following 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 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 constant.

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.

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 represented.

To obtain the number of clock ticks per second returned by the () function, applications should call (_SC_CLK_TCK). See times(2) and sysconf(3C).

time(2), utime(2), clock(3C), clock_settime(3C), ctime(3C), difftime(3C), getdate(3C), mktime(3C), nanosleep(3C), strftime(3C), strptime(3C), timer_create(3C), timer_delete(3C), timer_settime(3C), timespec_get(3C), types.h(3HEAD), attributes(7), standards(7)

January 12, 2025 OmniOS