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TIMERADD(3) Linux Programmer's Manual TIMERADD(3)
timeradd, timersub, timercmp, timerclear, timerisset - timeval operations
#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: _BSD_SOURCE
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: 1970-01-01 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(..., !=)
timerisset() and timercmp() return true (nonzero) or false (0).
No errors are defined.
Not in POSIX.1-2001. Present on most BSD derivatives.
gettimeofday(2), time(7)
This page is part of release 3.32 of the Linux man-pages project. A
description of the project, and information about reporting bugs, can be found
at http://www.kernel.org/doc/man-pages/.
Linux 2010-02-25 TIMERADD(3)
HTML rendering created 2010-12-03 by Michael Kerrisk, author of The Linux Programming Interface