1.\" Copyright (c) 1990, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" This code is derived from software contributed to Berkeley by 5.\" the American National Standards Committee X3, on Information 6.\" Processing Systems. 7.\" 8.\" Redistribution and use in source and binary forms, with or without 9.\" modification, are permitted provided that the following conditions 10.\" are met: 11.\" 1. Redistributions of source code must retain the above copyright 12.\" notice, this list of conditions and the following disclaimer. 13.\" 2. Redistributions in binary form must reproduce the above copyright 14.\" notice, this list of conditions and the following disclaimer in the 15.\" documentation and/or other materials provided with the distribution. 16.\" 3. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" @(#)clock.3 8.1 (Berkeley) 6/4/93 33.\" $FreeBSD: src/lib/libc/gen/clock.3,v 1.6.2.4 2002/02/16 14:08:46 dwmalone Exp $ 34.\" $DragonFly: src/lib/libc/gen/clock.3,v 1.3 2004/03/11 12:28:50 hmp Exp $ 35.\" 36.Dd June 4, 1993 37.Dt CLOCK 3 38.Os 39.Sh NAME 40.Nm clock 41.Nd determine processor time used 42.Sh LIBRARY 43.Lb libc 44.Sh SYNOPSIS 45.In time.h 46.Ft clock_t 47.Fn clock void 48.Sh DESCRIPTION 49The 50.Fn clock 51function 52determines the amount of processor time used since the invocation of the 53calling process, measured in 54.Dv CLOCKS_PER_SEC Ns s 55of a second. 56.Sh RETURN VALUES 57The 58.Fn clock 59function returns the amount of time used unless an error occurs, in which 60case the return value is \-1. 61.Sh SEE ALSO 62.Xr getrusage 2 , 63.Xr clocks 7 64.Sh STANDARDS 65The 66.Fn clock 67function conforms to 68.St -isoC . 69However, 70.St -susv2 71requires 72.Dv CLOCKS_PER_SEC 73to be defined as one million. 74.Dx 75does not conform to this requirement; 76changing the value would introduce binary incompatibility 77and one million is still inadequate on modern processors. 78