From: Adam Shelly <adam.shelly@...>
Date: 2006-01-20T15:06:22+09:00
Subject: Re: Ruby Quiz #62

On 1/19/06, James Edward Gray II <james@grayproductions.net> wrote:
> On Jan 19, 2006, at 8:06 PM, Adam Shelly wrote:
> > irb(main):013:0> r=1...9
> > => 1...9
> > irb(main):014:0> r.last
> > => 9
> > irb(main):015:0> r.include? r.last
> > => false
> >
> > I really expected (1...9).last to return 8.   I guess this is just
> > another way ranges are screwy.
>
> Na, that's not odd at all.  Just tell yourself .. is inclusive
> and ... is exclusive (with regards to the last member).  See how that
> extra dot pushes it off the end there...  ;)
>
That part I know.  But I expected (1...x) to be exactly equivalent to (1..x-1)
The difference bit me when I was trying to write a version of rand
that took a range (It would be nice if that was a built-in...).  My
first attempt is below, but it returns the wrong results when rng is
an exclusive range.
def rrand rng
  rng.first + rand(rng.last-rng.first)
end

-Adam