HP-UX Reference (11i v1 05/09) - 2 System Calls (vol 5)

g
gettimeofday(2) gettimeofday(2)
HP-UX EXTENSIONS
SYNOPSIS
#include <sys/time.h>
int gettimeofday(struct timeval *tp,
struct timezone *tzp);
DESCRIPTION
When gettimeofday()
is called under HP-UX, extensions apply to the time zone parameter, the return
value, and errors.
If the
tzp parameter is not a null pointer, it is interpreted as a pointer to a
struct timezone under
HP-UX. The
struct timezone has the following fields:
tz_minuteswest The number of minutes that the local time zone is west of UTC.
tz_dsttime A flag that, if nonzero, indicates that Daylight Savings Time (DST) applies locally during
the appropriate part of the year.
Programs should use this time zone information only in the absence of the
TZ environment variable.
Security Restrictions
Only a user with appropriate privileges can set the time of day.
RETURN VALUE
gettimeofday() return 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. The reliable detection of this error
is implementation dependent.
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
The microsecond value usually has a granularity much greater than one due to the resolution of the system
clock. Relying on any granularity (particularly of one) will render code nonportable.
Section 2−−122 Hewlett-Packard Company − 1 − HP-UX 11i Version 1: September 2005