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Manual

timeradd

NAME
LIBRARY
SYNOPSIS
DESCRIPTION
RETURN VALUE
ERRORS
STANDARDS
HISTORY
SEE ALSO

NAME

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

LIBRARY

Standard C library ( libc , -lc )

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:
Since glibc 2.19:
_DEFAULT_SOURCE
glibc 2.19 and earlier:
_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.

STANDARDS

None.

HISTORY

BSD.

SEE ALSO

gettimeofday (2), time (7)