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Daylight savings time
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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 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: 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 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 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 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. 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 represented. 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 ALSO
time(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)
