clock(3C)
NAME
clock - report CPU time used
SYNOPSIS
#include <time.h>
clock_t clock(void);
DESCRIPTION
The clock() function returns the amount of CPU time (in
microseconds) used since the first call to clock() in the
calling process. The time reported is the sum of the user
and system times of the calling process and its terminated
child processes for which it has executed the wait(2) func-
tion, the pclose(3C) function, or the system(3C) function.
RETURN VALUES
Dividing the value returned by clock() by the constant
CLOCKS_PER_SEC, defined in the <time.h> header, will give
the time in seconds. If the process time used is not avail-
able or cannot be represented, clock returns the value
(clock_t) -1.
USAGE
The value returned by clock() is defined in microseconds for
compatibility with systems that have CPU clocks with much
higher resolution. Because of this, the value returned will
wrap around after accumulating only 2147 seconds of CPU time
(about 36 minutes).
ATTRIBUTES
See attributes(5) for descriptions of the following attri-
butes:
____________________________________________________________
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
|_____________________________|_____________________________|
| MT-Level | MT-Safe |
|_____________________________|_____________________________|
SEE ALSO
times(2), wait(2), popen(3C), system(3C), attributes(5)
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