timeradd(3) - Linux manual page (original) (raw)

timeradd(3) Library Functions Manual timeradd(3)

NAME top

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

LIBRARY top

   Standard C library (_libc_, _-lc_)

SYNOPSIS top

   **#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 top

   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->tvusec_ 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->tvusec_ 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 top

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

ERRORS top

   No errors are defined.

STANDARDS top

   None.

HISTORY top

   BSD.

SEE ALSO top

   [gettimeofday(2)](../man2/gettimeofday.2.html), [time(7)](../man7/time.7.html)

COLOPHON top

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Linux man-pages 6.10 2024-07-23 timeradd(3)

Pages that refer to this page:gettimeofday(2), timeval(3type), time(7)