timeradd,   timersub,   timercmp,   timerclear,  timerisset  -  timeval


   #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:
       Glibc 2.19 and earlier:


   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

   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(..., !=)


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


   No errors are defined.


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


   gettimeofday(2), time(7)


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   description  of  the project, information about reporting bugs, and the
   latest    version    of    this    page,    can     be     found     at


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