NAME
time —
get time of day
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <time.h>
time_t
time(
time_t
*tloc);
DESCRIPTION
The
time() function returns the value of time in seconds since
0 hours, 0 minutes, 0 seconds, January 1, 1970, Coordinated Universal Time.
A copy of the time value may be saved to the area indicated by the pointer
tloc. If
tloc is a
NULL
pointer, no value is stored.
Upon successful completion,
time() returns the value of time.
Otherwise a value of ((
time_t) -1) is returned and the
global variable
errno is set to indicate the error.
ERRORS
No errors are defined.
SEE ALSO
gettimeofday(2),
ctime(3)
STANDARDS
The
time() function conforms to
IEEE Std
1003.1-1990 (“POSIX.1”).
HISTORY
A
time() function appeared in
Version 2
AT&T UNIX. It returned a 32-bit value measuring sixtieths of a
second, leading to rollover every 2.26 years. In
Version 6 AT&T UNIX, the precision of
time() was changed to seconds, allowing 135.6 years between
rollovers.
In
NetBSD 6.0 the
time_t type was
changed to be 64 bits wide, including on 32-bit machines, making rollover a
concern for the far distant future only. Note however that any code making the
incorrect assumption that
time_t is the same as
long will fail on 32-bit machines in 2038.