NAME
timeradd, timersub, timercmp, timerclear, timerisset - timeval operations
LIBRARY
Standard C library (libc, -lc)
SYNOPSIS
#include <sys/time.h>void timeradd(struct timeval *\na\n, struct timeval *\nb\n,\n
\n struct timeval *\nres\n);\n
\nvoid timersub(struct timeval *\na\n, struct timeval *\nb\n,\n
\n struct timeval *\nres\n);void timerclear(struct timeval *\ntvp\n);\n
\nint timerisset(struct timeval *\ntvp\n);int timercmp(struct timeval *\na\n, struct timeval *\nb\n, \nCMP\n);All functions shown above:
\n
Since glibc 2.19:
\n
_DEFAULT_SOURCE
\n
glibc 2.19 and earlier:
\n
_BSD_SOURCEDESCRIPTION
The macros are provided to operate on timeval structures, defined in <sys/time.h> as:
struct timeval {
\n
time_t tv_sec; /* seconds */
\n
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)