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From: jhz@cunixa.cc.columbia.edu (Jennifer H. Zemsky)
Newsgroups: comp.lang.c
Subject: Re: random numbers in c
Message-ID: <1991Apr27.142620.6859@cunixf.cc.columbia.edu>
Date: 27 Apr 91 14:26:20 GMT
References: <9104261022.aa28844@Bonnie.ics.uci.edu>
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Reply-To: jhz@cunixa.cc.columbia.edu (Jennifer H. Zemsky)
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sto@Bonnie.ICS.UCI.EDU writes:
>	does anyone know how to generate random numbers in c from X to
>Y , where  X and Y can be postive or negative ?

i assume you want a random integer on the range [X,Y]
this is a routine that i use. it works for me.
this should work for positive and/or negative values of high and low.

if you want non-integers, chagne the value of modsize to high-low
and remove the (int) cast from the return line. snafu: the range
for non-integers is [low,high).

i don't think that you need any extra #include libraries... maybe math.h ?


-----cut---here-----
int Random (low, high)
	int low, high;
{
	int modsize = high-low+1;
	double valu;

	valu = drand48();         /* [0,1) */
	valu *= modsize;          /* [0, modsize)*/
	valu += low;              /* [low, high+1)*/
	return ((int) valu);      /*[low, high]*/
}
-----cut---here-----

--hymie
jhz@cunixa.cc.columbia.edu
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note: the above information, knowledge, etc. is offered only on an
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