временные операции (timeval operations)
Имя (Name)
timeradd, timersub, timercmp, timerclear, timerisset - timeval
operations
Синопсис (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
Описание (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: 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(..., !=)
Возвращаемое значение (Return value)
timerisset() and timercmp() return true (nonzero) or false (0).
Ошибки (Error)
No errors are defined.
Стандарты (Conforming to)
Not in POSIX.1. Present on most BSD derivatives.
Смотри также (See also)
gettimeofday(2), time(7)
