From: Sam Sungshik Kong <ssk@...>
Date: 2004-07-22T05:52:02+09:00
Subject: Re: substring by range parameter (bug?)

Hi, Ara!

I understand what you mean.
However, the return values should be consistent even if the range object
doesn't make sense.

> > s[-1..-2]    #=> ""
> > s[-1..-3]    #=> nil
How would you explain the inconsistency?

The only explanation I can think of is:

s[-1..-1] #=>"9"
s[-1..-2] #=>"", because one step back, one less character...
s[-1..-3] #=>nil, because there's no "less character" concept beyond empty
string.

Sam

"Ara.T.Howard" <ahoward@noaa.gov> wrote in message
news:Pine.LNX.4.60.0407211408090.19495@harp.ngdc.noaa.gov...
> On Thu, 22 Jul 2004, D T wrote:
>
> > s="0123456789"
> > s[-1..-2]    #=> ""
> > s[-2..-1]    #=> "89"
> > s[-1..-3]    #=> nil
> > s[-3..-1]    #=> "789"
> > s[-1..-2] = "..." ; s #=> "012345678...9"
> >
> > Expect s[-1..-2] returns nil as s[-1..-3]. (bug ? it returns empty
string
> > instead of nil.)
>
>
> for ranges, start must be <= end and -1 is not <= -2
>
> eg. for the string "foobar":
>
>      ---- --- ----
>      char idx nidx
>      ---- --- ----
>      f    0    -6
>      o    1    -5
>      o    2    -4
>      b    3    -3
>      a    4    -2
>      r    5    -1
>
>    ~ > irb
>    irb(main):001:0> "foobar"[-2..-1]
>    => "ar"
>    irb(main):002:0> "foobar"[-6..-4]
>    => "foo"
>    irb(main):003:0> "foobar"[-3..-1]
>    => "bar"
>
> cheers.
>
> -a
> --
>
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> | EMAIL   :: Ara [dot] T [dot] Howard [at] noaa [dot] gov
> | PHONE   :: 303.497.6469
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> | and a weed grows, even though we do not love it.
> |   --Dogen
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