[Pharo-project] digitAt: issue

Bernat Romagosa tibabenfortlapalanca at gmail.com
Tue May 3 10:54:49 CEST 2011


Done: http://code.google.com/p/pharo/issues/detail?id=4154

2011/5/2 Stéphane Ducasse <stephane.ducasse at inria.fr>

> open an issue and propose a path to get there
>
> Stef
>
> On May 2, 2011, at 3:34 PM, Camillo Bruni wrote:
>
> > DigitAt: is a horrible name then, should rather be bitAt:.
> >
> > the digitAt: implementation you're looking for:
> >
> >       ^ self // (10 raisedTo: index - 1) \\ 10
> >
> > thats quite short :)
> >
> > On 2011-05-02, at 11:35, Bernat Romagosa wrote:
> >
> >> Ouch, understood!
> >>
> >> Then what would be the proper way to address a decimal digit in a
> number? I can only think of (bigNumber asString at: index) asNumber, which
> is... awful.
> >>
> >> 2011/5/2 Sven Van Caekenberghe <sven at beta9.be>
> >> Bernat,
> >>
> >> On 02 May 2011, at 11:13, Bernat Romagosa wrote:
> >>
> >> > Hi, try to run the following:
> >> >
> >> > (2 raisedTo: 100000) digitAt: 1
> >> >
> >> > The expected result (if I understood what digitAt: should return) is
> 9, but the message returns 0 instead. In fact, it returns 0 for any index.
> >> >
> >> > Is this a bug or am I missunderstanding how digitAt: should work?
> >> >
> >> > Cheers,
> >> >
> >> > Bernat Romagosa.
> >> >
> >> > p.s. My config is Pharo 1.2 with a 'Croquet Closure Cog VM
> [CoInterpreter VMMaker-oscog.51]' on Debian Lenny.
> >>
> >> Consider,
> >>
> >> 2 raisedTo: 32
> >>
> >> #digitAt: for digits 1 to 4 returns 0, 5 return 1.
> >> From the comments you can see that the number is looked at in base 256.
> >> The above number thus has 5 digits in this base, four are zero and the
> highest one is one.
> >> Furthermore, the first digit is the lowest one.
> >> If you inspect the number it might become clearer.
> >>
> >> Any #digitAt: has to depend on the base you use to represent the number,
> this one doesn't, so it seems to be useful only to return internal parts of
> a number.
> >>
> >> HTH,
> >>
> >> Sven
> >>
> >>
> >>
> >
>
>
>
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