From: Robert Klemme <bob.news@...>
Date: 2005-09-06T16:48:49+09:00
Subject: Re: [Q] how to do insertion and smooth traversal simultaneously on array

SHIGETOMI, Takuhiko wrote:
> greetings, guys.
>
> this is a pseudo-ruby code which shows what i am expecting.
>
> a = [ 0, 1, 2, 3, 4, 5 ]
> a.each_with_index do |x, i|
>   puts "[#{i}] : #{x}"
>   if i % 2 == 0  # even index ?
>     a.insert( i, ':-)' )
>     skip 1 # <- this is a pseudo directive to skip the next element
>            #    which has just been inserted now
>   end
> end
> puts a.size
>
> expected output...
>
> [0] : 0
> [1] : 1
> [2] : 2
> [3] : 3
> [4] : 4
> [5] : 5
> 9         <-- means that 3 smileys have been inserted
>
> as above, i want to traverse an array with some conditional insertion
> to itself.
>
> do anyone know cool way for that?

The easiest is probably to use the index for iterating and adjust it on
insertions.  The alternative is to remember insertions and apply them
after the iteration (probably in reverse order to avoid complicated index
calculations).

Kind regards

    robert