c++, how to obtain the time?/have a counter?

[Lain]

Anyone here knows?

[rg3]

The time() function:

time_t time(time *t);

can be used to obtain the number of seconds since the Epoch. It's listed as part of the C library in the K&R book, but my manpage doesn't mention ANSI/ISO C as one of the standards the function is conformant to.

In any case, if you want to know how many CPU seconds have been used by your program (a "good" way to measure time differences), you should use the clock() function and divide the result by CLOCKS_PER_SEC:

clock_t clock(void);

It's supposed to be ANSI C.

[Lain]

Thank you, i will check that out. by the way what is Epoch? http://forums.3drealms.com/ubbthreads/images/graemlins/confused.gif

[rg3]

TIME(2) Linux Programmer’s Manual TIME(2)



NAME
time - get time in seconds

SYNOPSIS
#include <time.h>

time_t time(time_t *t);

DESCRIPTION
time returns the time since the Epoch (00:00:00 UTC, Jan*
uary 1, 1970), measured in seconds.

If t is non-NULL, the return value is also stored in the
memory pointed to by t.

RETURN VALUE
On success, the value of time in seconds since the Epoch
is returned. On error, ((time_t)-1) is returned, and
errno is set appropriately.

ERRORS
EFAULT t points outside your accessible address space.

NOTES
POSIX.1 defines seconds since the Epoch as a value to be
interpreted as the number of seconds between a specified
time and the Epoch, according to a formula for conversion
from UTC equivalent to conversion on the naïve basis that
leap seconds are ignored and all years divisible by 4 are
leap years. This value is not the same as the actual num*
ber of seconds between the time and the Epoch, because of
leap seconds and because clocks are not required to be
synchronised to a standard reference. The intention is
that the interpretation of seconds since the Epoch values
be consistent; see POSIX.1 Annex B 2.2.2 for further
rationale.

CONFORMING TO
SVr4, SVID, POSIX, X/OPEN, BSD 4.3
Under BSD 4.3, this call is obsoleted by gettimeofday(2).
POSIX does not specify any error conditions.

SEE ALSO
ctime(3), date(1), ftime(3), gettimeofday(2)



Linux 2.0.30 1997-09-09 TIME(2)