Adding to an array during iteration

Question

Why does this code “block” a ruby? And what is the best way to overcome this? I posted the solution below. Is there any other way to do this? Thanks in advance!

the code:

nums = [1, 2, 3] nums.each { |i| nums << i + 1 } 

My decision:

 nums = [1, 2, 3] adjustments = [] nums.each { |i| adjustments << i + 1 } nums += adjustments 

Answer 1

This is because everyone uses an enumerator (so it never reaches the end if you keep adding to it).

You can duplicate an array before applying each of them.

 nums = [1, 2, 3] nums.dup.each { |i| nums << i + 1 } 

Another way is to add additional elements defined by the map:

 nums = [1, 2, 3] nums += nums.map { |i| i + 1 } 

Answer 2

 nums = [1, 2, 3] nums.each { |i| nums << i + 1 } 

You add to the array as you iterate over it, so it never finishes executing.