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NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | STANDARDS | HISTORY | SEE ALSO | COLOPHON |
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timeradd(3) Library Functions Manual timeradd(3)
timeradd, timersub, timercmp, timerclear, timerisset - timeval
operations
Standard C library (libc, -lc)
#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.
None.
BSD.
gettimeofday(2), time(7)
This page is part of the man-pages (Linux kernel and C library
user-space interface documentation) project. Information about
the project can be found at
⟨https://www.kernel.org/doc/man-pages/⟩. If you have a bug report
for this manual page, see
⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.
This page was obtained from the tarball man-pages-6.15.tar.gz
fetched from
⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on
2025-08-11. If you discover any rendering problems in this HTML
version of the page, or you believe there is a better or more up-
to-date source for the page, or you have corrections or
improvements to the information in this COLOPHON (which is not
part of the original manual page), send a mail to
man-pages@man7.org
Linux man-pages 6.15 2025-05-17 timeradd(3)
Pages that refer to this page: gettimeofday(2), timeval(3type), time(7)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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