TIMERADD(3)                                         Linux Programmer's Manual                                        TIMERADD(3)



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

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: _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 normal-
       ized 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() implementa-
       tion, 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.

CONFORMING TO
       Not in POSIX.1-2001.  Present on most BSD derivatives.

SEE ALSO
       gettimeofday(2), time(7)

COLOPHON
       This page is part of release 3.25 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)