From:	Erik Max Francis <max AT alcyone DOT com>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: Random numbers
Date:	Fri, 30 May 1997 14:04:46 -0700
Organization:	Alcyone Systems
Lines:	23
Message-ID:	<338F40EE.5244E66@alcyone.com>
References:	<01bc6ce9$72076bc0$363e63c3 AT 8652hvt73761>
NNTP-Posting-Host:	newton.alcyone.com
Mime-Version:	1.0
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

Matthew Bennett wrote:

> When using the 'random' command in the form:
> 
> printf("%d\n", random() & 10);
> 
> The numbers produced are always either 0, 2, 8 or 10.

That's because you're bitwise and'ing.  What you meant to do was use the
modulo operator %.

You can use the & operator for this kind of bounding when the bound is a
power of two, in which case you bitwise and with one less than that.
However, it can only be used in that special case when it is a power of
two, and 10 most certainly is not.

-- 
       Erik Max Francis, &tSftDotIotE / email / max AT alcyone DOT com
                     Alcyone Systems /   web / http://www.alcyone.com/max/
San Jose, California, United States /  icbm / 37 20 07 N  121 53 38 W
                                   \
     "Covenants without the sword / are but words."
                                 / Camden

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