From: benjohn@...
Date: 2007-07-13T21:57:31+09:00
Subject: Re: Loop over an array that changes the elements

> Hi,
>
> I have a rather simple question. I have an array and want to change the
> elements of the array in a loop. For example in Java, you would write:
>
> int[] numbers = {1, 2, 3}
>
> for(int i = 0; i < numbers.length; i++)
> {
>    numbers[i] = numbers[i] * 2
> }
>
>
> In Ruby the common way to loop over an array is Array#each
>
> But
>
> numbers = [1, 2, 3]
>
> numbers.each do |num|
>   num = num * 2
> end
>
> would not change the array itself.

You're right.

As others and I have said, the map solution is good here.

  numbers = numbers.map {|number| number*2}

If you really wanted to change the array itself though, you could do this:

  numbers.each_index {|i| numbers[i] = numbers[i] * 2}

or

  numbers.each_index {|i| numbers[i] *= 2}

Thanks,
  Benj