Re: Problems with Test

[James Mckenzie]

Charles Davis  wrote:
> On 10/31/10 9:23 PM, James McKenzie wrote:
> > All:
> >
> > I'm trying to convert one integer number using a float number factor. 
> > Here is the code:
> >
> > int ry = 125;
> > double ryf;
> >
> > ryf = ry/1440;
> >
> > The result is 0 and should be 0.06666666667 (or even more sixes.)
>
> And why should it be? None of the values in the expression 'ry/1440' are
> of type 'double'. They're both 'int's, so the compiler sees it as
> integer division instead of FP division. The C language spec doesn't
> require the compiler to infer that you wanted FP division when you
> assign to a variable of FP type.

Ah, the wonders of 'c'.  Thank you for the reminder that this is what happens during this division process.  Been a long time since I've tried this.
> > What am I doing 'incorrectly'?
>
> Now, if your assignment looked like this:
>
> ryf = ry/1440.0;
>
> then it would work correctly. Now the 1440 is of type 'double', so the
> compiler emits a floating-point division.

Got it.  I tried to cast ry to double, but that did not work.  Guess my version of gcc has a problem or I did it wrong.

Will try changing the division this evening and see what happens.

James McKenzie

Problems with Test

[Hin-Tak Leung]

--- On Mon, 1/11/10, James Mckenzie  wrote:
> From: James Mckenzie 
> Subject: Re: Problems with Test
> To: "Charles Davis" 
> Cc: "[e-mail]" 
> Date: Monday, 1 November, 2010, 14:26
> Charles Davis 
> wrote:
> > On 10/31/10 9:23 PM, James McKenzie wrote:
> > > All:
> > >
> > > I'm trying to convert one integer number using a
>
> float number factor.
> > > Here is the code:
> > >
> > > int ry = 125;
> > > double ryf;
> > >
> > > ryf = ry/1440;

<snipped>
> Got it.  I tried to cast ry to double, but that did
> not work.  Guess my version of gcc has a problem or I
> did it wrong.

<snipped>

- ryf = ((double) ry)/1440; - should work#
 - ryf = (double) ry/1440;   - does not work, because it is equivalent to
                               "(double) (ry/1440) " (still integer division).

So it depends on how you did cast, really.