From: Stefano Crocco <stefano.crocco@...>
Date: 2007-12-11T18:28:00+09:00
Subject: Re: Find the first non-nil element in an array

Alle marted́ 11 dicembre 2007, lianliming ha scritto:
> Hi all,
>
> Is there any build-in method of class Array which can be used to find
> the first non-nil element in an array? I can't find any so I am trying
> to achieve it by my own approach. I don't think my approach is smart
> enough, so I would like to know better one to do so. Here is what I am
> doing:
>
> a = [nil, "hello", "world"]
> b = a
> b.compact!
> first_non_nil_elem =  b.first
>
> I don't call "compact!" directly on a because it will change a's
> structure, I want to reserve nil elements in a.
>
> Any suggestions are really appreciated!

You can use Enumerable#find, which will return the first item in the array for 
which the block returns true:

a = [nil, "hello", "world"]
puts a.find{|i| !i.nil?}
=> "hello"

By the way, you can use compact, instead of compact! to avoid using the 
temporary variable b:

a = [nil, "hello", "world"]
first_non_nil_elem = a.compact.first

While compact! removes the nil elements from the receiver, compact returns a 
new array with the nil element removed.

I hope this helps

Stefano