Manpages - timeradd.3

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

  #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

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(…, !=)

*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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