1.\" $NetBSD: rand.3,v 1.12 2010/03/22 19:30:54 joerg Exp $ 2.\" 3.\" Copyright (c) 1990, 1991, 1993 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" This code is derived from software contributed to Berkeley by 7.\" the American National Standards Committee X3, on Information 8.\" Processing Systems. 9.\" 10.\" Redistribution and use in source and binary forms, with or without 11.\" modification, are permitted provided that the following conditions 12.\" are met: 13.\" 1. Redistributions of source code must retain the above copyright 14.\" notice, this list of conditions and the following disclaimer. 15.\" 2. Redistributions in binary form must reproduce the above copyright 16.\" notice, this list of conditions and the following disclaimer in the 17.\" documentation and/or other materials provided with the distribution. 18.\" 3. Neither the name of the University nor the names of its contributors 19.\" may be used to endorse or promote products derived from this software 20.\" without specific prior written permission. 21.\" 22.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32.\" SUCH DAMAGE. 33.\" 34.\" from: @(#)rand.3 8.1 (Berkeley) 6/4/93 35.\" 36.Dd June 4, 1993 37.Dt RAND 3 38.Os 39.Sh NAME 40.Nm rand , 41.Nm srand , 42.Nm rand_r 43.Nd bad random number generator 44.Sh LIBRARY 45.Lb libc 46.Sh SYNOPSIS 47.In stdlib.h 48.Ft void 49.Fn srand "unsigned int seed" 50.Ft int 51.Fn rand void 52.Ft int 53.Fn rand_r "unsigned int *seed" 54.Sh DESCRIPTION 55.Bf -symbolic 56These interfaces are obsoleted by 57.Xr random 3 . 58.Ef 59.Pp 60The 61.Fn rand 62function computes a sequence of pseudo-random integers in the range 63of 0 to 64.Dv RAND_MAX 65(as defined by the header file 66.In stdlib.h ) . 67.Pp 68The 69.Fn srand 70function sets its argument as the seed for a new sequence of 71pseudo-random numbers to be returned by 72.Fn rand . 73These sequences are repeatable by calling 74.Fn srand 75with the same seed value. 76.Pp 77If no seed value is provided, the 78.Fn rand 79function is automatically seeded with a value of 1. 80.Pp 81The 82.Fn rand_r 83function is a reentrant interface to 84.Fn rand ; 85the seed has to be supplied and is maintained by the caller. 86.Sh SEE ALSO 87.Xr random 3 , 88.Xr rnd 4 89.Sh STANDARDS 90The 91.Fn rand 92and 93.Fn srand 94functions 95conform to 96.St -ansiC . 97The 98.Fn rand_r 99function conforms to 100.St -p1003.1c-95 . 101