Path: utzoo!utgpu!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!purdue!decwrl!sgi!arisia!quintus!ok
From: ok@quintus
Newsgroups: comp.bugs.4bsd
Subject: SunOS3.2 rand(3) manual error
Message-ID: <753@quintus.UUCP>
Date: 27 Nov 88 05:44:23 GMT
Sender: news@quintus.UUCP
Reply-To: ok@quintus ()
Organization: Quintus Computer Systems, Inc.
Lines: 24


The SunOS 3.2 on-line manual page for rand(3v) says:
     rand uses a multiplicative congruential random  number  gen-
     erator  with period 2**32 to return successive pseudo-random
     numbers in the range from 0 to (2**15)-1.

In fact it generates 31-bit integers, as the following test program shows:
main()
    {
	extern int rand();
	extern void srand();
	int i;

	srand(21345);
	for (i = 1; i <= 20; i++) printf("%12d\n", rand());
    }
--

This program generates identical results on a Sun-3/60 and a Sequent 386.
The Sequent documentation describes the range correctly.

The SVID specifies 15-bit results.  The BSD/SV incompatibility is known, but
it looked as though SunOS 3.2 had adopted the SV definition.  Nope, you still
need	(rand()&32767) for portability.