man Pages(5): Headers, Tables and Macros

time(5)

NAME | SYNOPSIS | DESCRIPTION | USAGE | SEE ALSO

NAME

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 [0,61]
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.

This header defines the following symbolic names:

NULL: Null pointer constant.
CLK_TCK: Number of clock ticks per second returned by the times(2) function.
CLOCKS_PER_SEC: A number used to convert the value returned by the clock(3C) function into seconds.

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

time_t  tv_sec    seconds
long    tv_nsec   nanoseconds

This header also declares the itimerspec structure, which has at least 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 systemwide realtime clock.
TIMER_ABSTIME: Flag indicating time is absolute with respect to the clock associated with a timer.

The clock_t, size_t and time_t types are defined as described in <sys/types.h>.

Although the value of CLOCKS_PER_SEC is 1 million on all Solaris systems, it may be variable on other systems and it should not be assumed that CLOCKS_PER_SEC is a compile-time constant.

The value of CLK_TCK is currently the same as the value of sysconf(_SC_CLK_TCK); however, new applications should call sysconf(3C) because the CLK_TCK macro may be withdrawn in a future issue.

The <time.h> header provides a declaration for getdate_err.

The following are declared as variables:

extern int       daylight;
extern long int  timezone;
extern char      *tzname[];

USAGE

The range [0,61] for tm_sec allows for the occasional leap second or double leap second.

tm_year is a signed value, therefore years before 1900 may be represented.