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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);

       void timerisset(struct timeval *tvp);

       void 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  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() zeroes out the timeval structure pointed  to  by  tvp,  so
       that  it  represents  the  time at midnight on the morning of 1 January
       1970 (the Epoch).

       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.

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 2.77 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/.