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   timersub    ( 3 )

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Имя (Name)

timeradd, timersub, timercmp, timerclear, timerisset - timeval
       operations

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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

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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(..., !=)

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Возвращаемое значение (Return value)

timerisset() and timercmp() return true (nonzero) or false (0).

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Ошибки (Error)

No errors are defined.

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Стандарты (Conforming to)

Not in POSIX.1.  Present on most BSD derivatives.

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Смотри также (See also)

gettimeofday(2), time(7)

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