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From: devine@shodha.dec.com (Bob Devine)
Newsgroups: comp.lang.c
Subject: Re: Nude Vicar in Sex Romp!
Summary: double, double, toil and trouble
Message-ID: <387@shodha.dec.com>
Date: 21 Aug 89 17:14:38 GMT
References: <960@prlhp1.prl.philips.co.uk>
Organization: Digital Equipment Corp. - Colorado Springs, CO.
Lines: 18

In article <960@prlhp1.prl.philips.co.uk>, yuleat@prlhp1.prl.philips.co.uk (yuleat) writes:
> fn2(x, y)
> float *x, *y;
>  {
>     printf("In fn2 values are x= %f & y= %f\n", *x, *y);
>  }
> 
> What I would like to know is whether this is what the compiler
> should do (I've looked in K&R and I couldn't find anything
> that addressed this problem specifically).

  Check out the sections on parameter widening.  The floats (likely
these are 4 bytes) are being widened to doubles (8 bytes) so when
you use a `float *' you are only getting 1/2 the number.  On some
machines a hardware check for a valid floating point number is made
so if you had bad luck to select the wrong bit pattern the program
would have dumped with a very misleading error!

Bob Devine