timerisset

Langue: en

Version: 2010-02-25 (ubuntu - 24/10/10)

Section: 3 (Bibliothèques de fonctions)

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: _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.1-2001. Present on most BSD derivatives.

SEE ALSO

gettimeofday(2), time(7)

COLOPHON

This page is part of release 3.24 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/.