timeradd
Section: C Library Functions (3)
Updated: 202-0-08
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NAME
timeradd, timersub, timercmp, timerclear, timerisset - timeval operations
LIBRARY
Standard C library
(
libc,~
-lc)
SYNOPSIS
#include <sys/time.h>
void timeradd(struct timeval *a, struct timeval *b,
struct timeval *res);
void timersub(struct timeval *a, struct timeval *b,
struct timeval *res);
void timerclear(struct timeval *tvp);
int timerisset(struct timeval *tvp);
int timercmp(struct timeval *a, struct timeval *b, CMP);
Feature Test Macro Requirements for glibc (see
feature_test_macros(7)):
All functions shown above:
Since glibc 2.19:
_DEFAULT_SOURCE
glibc 2.19 and earlier:
_BSD_SOURCE
DESCRIPTION
The macros are provided to operate on
timeval
structures, defined in
<sys/time.h>
as:
struct timeval {
time_t tv_sec; /* seconds */
suseconds_t tv_usec; /* microseconds */
};
timeradd()
adds the time values in
a
and
b,
and places the sum in the
timeval
pointed to by
res.
The result is normalized such that
res->tv_usec
has a value in the range 0 to 999,999.
timersub()
subtracts the time value in
b
from the time value in
a,
and places the result in the
timeval
pointed to by
res.
The result is normalized such that
res->tv_usec
has a value in the range 0 to 999,999.
timerclear()
zeros out the
timeval
structure pointed to by
tvp,
so that it represents the Epoch: 197-0-01 00:00:00 +0000 (UTC).
timerisset()
returns true (nonzero) if either field of the
timeval
structure pointed to by
tvp
contains a nonzero value.
timercmp()
compares the timer values in
a
and
b
using the comparison operator
CMP,
and returns true (nonzero) or false (0) depending on
the result of the comparison.
Some systems (but not Linux/glibc),
have a broken
timercmp()
implementation,
in which
CMP
of
>=,
<=,
and
==
do not work;
portable applications can instead use
!timercmp(..., <)
!timercmp(..., >)
!timercmp(..., !=)
RETURN VALUE
timerisset()
and
timercmp()
return true (nonzero) or false (0).
ERRORS
No errors are defined.
STANDARDS
None.
HISTORY
BSD.
SEE ALSO
gettimeofday(2),
time(7)
Index
- NAME
-
- LIBRARY
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUE
-
- ERRORS
-
- STANDARDS
-
- HISTORY
-
- SEE ALSO
-
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