From: Josh Cheek <josh.cheek@...>
Date: 2011-09-05T17:24:47+09:00
Subject: Re: loops problem

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On Mon, Sep 5, 2011 at 2:12 AM, Robert Klemme <shortcutter@googlemail.com>wrote:

> On Sun, Sep 4, 2011 at 5:21 PM, Josh Cheek <josh.cheek@gmail.com> wrote:
> > On Sun, Sep 4, 2011 at 9:45 AM, jack jones <shehio_22@hotmail.com>
> wrote:
> >
> >> I've read about the method which inserts some element in a certain place
> >> ..
> >> what I wanted to do is to shift all the elements to the back .. not
> >> inserting which will require rather complicated operation like deleting
> >> the element after shifting it .... I really don't understand the line
> >> you wrote, thank you :)
>
> > Insert nil. There are lots of options for docs.
> > rdoc.info:
> http://rdoc.info/stdlib/core/1.9.2/Array#insert-instance_method
> > ruby-doc.org: http://ruby-doc.org/core/classes/Array.html#M000230
> >
> > And you can't have an array with a "gap" in it. ie what is returned if
> you
> > access that index after you've shifted the elements? The obvious answer
> is
> > nil, so just insert nil:
> >
> > array = (0..10).to_a
> > counter = 5
> > array.insert counter, nil
> > array # => [0, 1, 2, 3, 4, nil, 5, 6, 7, 8, 9, 10]
>
> And if the length should stay the same an additional array.pop will
> remove the last element.
>
> Btw, for inserting multiple elements one can do:
>
> irb(main):004:0> a=10.times.to_a
> => [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
> irb(main):005:0> a[5,0] = Array.new 3
> => [nil, nil, nil]
> irb(main):006:0> a.pop 3
> => [7, 8, 9]
> irb(main):007:0> a
> => [0, 1, 2, 3, 4, nil, nil, nil, 5, 6]
> irb(main):008:0> a.length
> => 10
>
> Kind regards
>
> robert
>
> --
> remember.guy do |as, often| as.you_can - without end
> http://blog.rubybestpractices.com/
>
>
Insert takes multiple arguments, also.

a = *1..10
a # => [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

index = 5
a.insert index, *a.pop(3)
a # => [1, 2, 3, 4, 5, 8, 9, 10, 6, 7]

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