gettimeofda.2 (2010 09)

g
gettimeofday(2) gettimeofday(2)
NAME
gettimeofday - get the date and time
SYNOPSIS
#include <sys/time.h>
int gettimeofday(struct timeval *tp, void *tzp);
DESCRIPTION
The gettimeofday()
function obtains the current time, expressed as seconds and microseconds since
Epoch, and stores it in the
timeval
structure pointed to by tp.
The resolution of the system clock is one microsecond.
PARAMETERS
Programs should use this time zone information only in the absence of the
TZ environment variable.
tp A pointer to a
timeval structure in which the current time is returned.
The
timeval structure includes the following members:
time_t tv_sec /* Seconds. */
long tv_usec /* Microseconds. */
tzp If this parameter is not a null pointer, it is interpreted as a pointer to a
timezone structure under
HP-UX. The
timezone structure has the following fields:
tz_minuteswest The number of minutes that the local time zone is west of Coordinated Universal
Time (UTC) or Epoch.
tz_dsttime A flag that, if nonzero, indicates that Daylight Savings Time (DST) applies locally
during the appropriate part of the year.
RETURN VALUE
gettimeofday() returns the following values under HP-UX:
0 Successful completion.
-1 Failure. errno is set to indicate the error.
ERRORS
If
gettimeofday() fails,
errno is set to the following value under HP-UX:
[EFAULT] An argument address referenced invalid memory.
EXAMPLES
The following HP-UX example calls
gettimeofday()
twice. It then computes the lapsed time between
the calls in seconds and microseconds and stores the result in a timeval structure:
struct timeval first,
second,
lapsed;
struct timezone tzp;
gettimeofday (&first, &tzp);
/* lapsed time */
gettimeofday (&second, &tzp);
if (first.tv_usec > second.tv_usec) {
second.tv_usec += 1000000;
second.tv_sec--;
}
lapsed.tv_usec = second.tv_usec - first.tv_usec;
lapsed.tv_sec = second.tv_sec - first.tv_sec;
WARNINGS
Relying on a granularity of one microsecond may result in code that is not portable to other platforms.
HP-UX 11i Version 3: September 2010 − 1 − Hewlett-Packard Company 1