HP-UX Reference (11i v2 03/08) - 2 System Calls (vol 5)

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.
Section 2−−120 Hewlett-Packard Company − 1 − HP-UX 11i Version 2: August 2003