From: "Jan E." <lists@...>
Date: 2012-04-13T17:04:51+09:00
Subject: Re: How to test if array element exists?

Ralf Mueller wrote in post #1056271:
> On 04/13/2012 09:53 AM, Jan E. wrote:
>> end
>>
> what about this
> ?> array = [0,1,2,3]
> => [0, 1, 2, 3]
>  >> array[4]
> => nil
>  >> array[4].nil?
> => true
>  >> array[444].nil?
> => true
>  >> array[2].nil?
> => false
>  >>


This doesn't work, because nil may also be an actual element:

array = [nil]
puts array[0].nil?  # true
puts array[1].nil?  # true

So you cannot reliably tell if a certain element has been set (apart 
from the length solution mentioned above).

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