Why does Array#each return an array with the same elements?

Question

I\'m learning the details of how each works in ruby, and I tried out the following line of code:

p [1,2,3,4,5].each { |element| el }

Answer 1

Array#each

The block form of Array#each returns the original Array object. You generally use #each when you want to do something with each element of an array inside the block. For example:

[1, 2, 3, 4, 5].each { |element| puts element }

This will print out each element, but returns the original array. You can verify this with:

array = [1, 2, 3, 4, 5]
array.each { |element| element }.object_id === array.object_id
=> true

Array#map

If you want to return a new array, you want to use Array#map or one of its synonyms. The block form of #map returns a different Array object. For example:

array.object_id
=> 25659920
array.map { |element| element }.object_id
=> 20546920
array.map { |element| element }.object_id === array.object_id
=> false

You will generally want to use #map when you want to operate on a modified version of the original array, while leaving the original unchanged.