From: Eleanor McHugh <eleanor@...>
Date: 2009-05-09T08:32:06+09:00
Subject: Re: ruby string slice/[] w/ range, weird end behavior

On 9 May 2009, at 00:26, Gary Yngve wrote:
> First the docs:
>
> ...If passed two Fixnum objects, returns a substring starting at the
> offset given by the first, and a length given by the second. If given
> a range, a substring containing characters at offsets given by the
> range is returned... Returns nil if the initial offset falls outside
> the string, the length is negative, or the beginning of the range is
> greater than the end.
>
> Now from irb (1.8):
>
>>> "foo"[2..2]
> => "o"
>>> "foo"[3..3]
> => ""   # ????????
>>> "foo"[4..4]
> => nil
>
>>> "foo"[2,1]
> => "o"
>>> "foo"[3,1]
> => ""  # ????????
>>> "foo"[4,1]
> => nil
>
>>> "foo"[2]
> => 111  # (the 'o' char)
>>> "foo"[3]
> => nil  # This makes sense to me, but seems inconsistent wrt the above
>
> Seems to me like the null terminator of the string is somehow getting
> muddled into all of this.
>
> Is there any meaning/purpose behind this behavior?

String indices start at zero, so:

"foo"[0..0]			=> 'f'
"foo"[1..1]			=> 'o'
"foo"[2..2]			=> 'o'
"foo"[3..3]			=> nil


Ellie

Eleanor McHugh
Games With Brains
http://slides.games-with-brains.net
----
raise ArgumentError unless @reality.responds_to? :reason