[Rails] Re: Ruby: Array slice out of range?

viciousfish wrote in post #1016211:
> Hello,
>
> I am noodling with the Ruby Koans and I ran across an Array slice
> behavior that I just can't quite wrap my brain around:
>
> ruby-1.9.2-p180 :102 > array = [:peanut, :butter, :and, :jelly]
> => [:peanut, :butter, :and, :jelly]
> ruby-1.9.2-p180 :103 > array[4,0]
> => []
> ruby-1.9.2-p180 :104 > array[5,0]
> => nil
>
> from http://www.ruby-doc.org/core/classes/Array.html#M000267
> "Returns nil if the index (or starting index) are out of range."
>
> I don't understand why the 4th element is an empty array, whereas the
> 5th element is out of range. I would expect the 4th element to be out
> of range as 'array' contains elements 0-3.
>
> Can someone plz explain?
>

Slices are different than single indexes: array[4, 0] and array[4] point
to two different spots in the array, and the spot array[4,0] points to
is just inbounds, while array[4] is out of bounds. See here:

http://www.ruby-forum.com/topic/1393096

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