.\" Copyright (c) 1990, 1991 The Regents of the University of California.
.\" All rights reserved.
.\"
.\" This code is derived from software contributed to Berkeley by
.\" the American National Standards Committee X3, on Information
.\" Processing Systems.
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.\"	$OpenBSD: rand.3,v 1.5 1998/11/20 11:18:50 d Exp $
.\"
.Dd June 29, 1991
.Dt RAND 3
.Os
.Sh NAME
.Nm rand ,
.Nm srand
.Nd bad random number generator
.Sh SYNOPSIS
.Fd #include <stdlib.h>
.Ft void
.Fn srand "unsigned seed"
.Ft int
.Fn rand void
.Ft int
.Fn rand_r "unsigned int *seed"
.Sh DESCRIPTION
.Bf -symbolic
These interfaces are obsoleted by
.Xr random 3 .
.Ef
.Pp
The
.Fn rand
function computes a sequence of pseudo-random integers in the range
of 0 to
.Dv RAND_MAX
(as defined by the header file
.Aq Pa stdlib.h ) .
.Pp
The
.Fn srand
function sets its argument as the seed for a new sequence of
pseudo-random numbers to be returned by
.Fn rand .
These sequences are repeatable by calling
.Fn srand
with the same seed value.
.Pp
If no seed value is provided, the functions are automatically
seeded with a value of 1.
.Pp
The
.Fn rand_r
is a thread-safe version of
.Fn rand .
Storage for the seed must be provided through the
.Ar seed
argument, and needs to have been initialized by the caller.
.Sh SEE ALSO
.Xr arc4random 3 ,
.Xr rand48 3 ,
.Xr random 3
.Sh STANDARDS
The
.Fn rand
and
.Fn srand
functions
conform to
.St -ansiC .
.Pp
The
.Fn rand_r
function
conforms to ISO/IEC 9945-1 ANSI/IEEE
.Pq Dq Tn POSIX
Std 1003.1c Draft 10.