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. All advertising materials mentioning features or use of this software 17.\" must display the following acknowledgement: 18.\" This product includes software developed by the University of 19.\" California, Berkeley and its contributors. 20.\" 4. Neither the name of the University nor the names of its contributors 21.\" may be used to endorse or promote products derived from this software 22.\" without specific prior written permission. 23.\" 24.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34.\" SUCH DAMAGE. 35.\" 36.\" @(#)clock.3 8.1 (Berkeley) 6/4/93 37.\" $FreeBSD: src/lib/libc/gen/clock.3,v 1.6.2.4 2002/02/16 14:08:46 dwmalone Exp $ 38.\" $DragonFly: src/lib/libc/gen/clock.3,v 1.3 2004/03/11 12:28:50 hmp Exp $ 39.\" 40.Dd June 4, 1993 41.Dt CLOCK 3 42.Os 43.Sh NAME 44.Nm clock 45.Nd determine processor time used 46.Sh LIBRARY 47.Lb libc 48.Sh SYNOPSIS 49.In time.h 50.Ft clock_t 51.Fn clock void 52.Sh DESCRIPTION 53The 54.Fn clock 55function 56determines the amount of processor time used since the invocation of the 57calling process, measured in 58.Dv CLOCKS_PER_SEC Ns s 59of a second. 60.Sh RETURN VALUES 61The 62.Fn clock 63function returns the amount of time used unless an error occurs, in which 64case the return value is \-1. 65.Sh SEE ALSO 66.Xr getrusage 2 , 67.Xr clocks 7 68.Sh STANDARDS 69The 70.Fn clock 71function conforms to 72.St -isoC . 73However, 74.St -susv2 75requires 76.Dv CLOCKS_PER_SEC 77to be defined as one million. 78.Dx 79does not conform to this requirement; 80changing the value would introduce binary incompatibility 81and one million is still inadequate on modern processors. 82