timeradd

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:
           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: 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(..., !=)

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

ERRORS
       No errors are defined.

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

SEE ALSO
       gettimeofday(2), time(7)

COLOPHON
       This page is part of release 5.03 of the Linux man-pages project.  A
       description of the project, information about reporting bugs, and the
       latest version of this page, can be found at
       https://www.kernel.org/doc/man-pages/.



Linux                             2017-09-15                       TIMERADD(3)