OpenEuphoria

RE: BUG! Erratic for loop behavior

• Posted by Andy Serpa <renegade at earthling.net> Mar 23, 2002
• 540 views

Rolf Schröder wrote:
> Andy Serpa wrote:
> > ...
> > ------------------------------
> > for i = 31.1 to 34.2 by .1 do
> >   ? i
> > end for
> > ------------------------------
> > stops at 34.1 (!), NOT as expected.
> >
> Hi Andy,
>
> that's ok. Look at this:
>
>     for i = 31.1 to 34.1 by 0.1 do
>         printf(1,"%20.15f\n",i)
>     end for
>
> and you will notice why: the decimal given value 0.1 is exactly
> representable in the computer for it has to stores it internally as an
> binary value with a limited number of bits. Actually, 0.1 (dec.) is has
> an unlimited binary representation: 0.0001100110011..... . This is the
> correct way to do it (have in mind that 31.1 and 34.1 are also not
> exactly representable!):
>
>     for i = 311 to 341 by 1 do
>         printf(1,"%20.15f\n",i/10)
>     end for
>

Yeah, that's not really good enough for me -- .1 should be .1 in a loop.
 The Euphoria manual even has an example under the FOR loop section
using a .3 "by" value...  Is this also a "feature"?