NAME

clock() − report CPU time used

SYNOPSIS

#include <time.h>

clock_t clock(void);

DESCRIPTION

clock() returns the amount of CPU time (in microseconds) used since the first call to clock().  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 wait() or system() (see wait(2) and system(3S)). To determine the time in seconds, the value returned by clock() should be divided by the value of the macro CLOCKS_PER_SEC. 

The resolution of the clock varies, depending on the hardware and on software configuration. 

If the processor time used is not available or its value cannot be represented, the function returns the value (clock_t)−1.

WARNINGS

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 wraps around after accumulating only 2147 seconds of CPU time (about 36 minutes). 

DEPENDENCIES

Series 300/400

The clock resolution is 20 milliseconds. 

Series 700/800

The default clock resolution is 10 milliseconds. 

SEE ALSO

times(2), wait(2), system(3S). 

STANDARDS CONFORMANCE

clock(): AES, SVID2, XPG2, XPG3, XPG4, ANSI C

Hewlett-Packard Company  —  HP-UX Release 9.10: April 1995