Path: chuka.playstation.co.uk!news
From: Craig Graham <c_graham@hinge.mistral.co.uk>
Newsgroups: scee.yaroze.programming.gnu_compiler
Subject: Re: printf works, code doesn't
Date: Thu, 16 Apr 1998 11:42:58 +0100
Organization: Intelligent Research
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Message-ID: <3535E0B1.3FDF2F4E@hinge.mistral.co.uk>
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Joshua Meeds wrote:

> Well, that was the actual code, but that line wasn't remmed out (I think
> it was my newsgroup poster that messed it up).  You know what fixed the
> problem?  I had to type cast the equation as a double, like so:
>
> Fun=(double)(((Y2-Y1) / (X2-X1));

The outer brackets mean that as all parameters are unsigned long int's,the result of the
division is truncated to an integer before casting to a
double - so you lose the fractional component. Also, as X1, etc, are
unsigned, the result of Y2-Y1 will always be unsigned, so you'll lose
any directional information from the calculation.

Try:

    Fun=((double)(Y2-Y1))/((double)(X2-X1));

or alternatively, make X1, etc, into doubles instead of u_long's.

Craig.

>