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

ruby arrays each self
Jeff Storey picture Jeff Storey · Jul 22, 2012 · Viewed 17.6k times · Source

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 }

And the result is an array of

[1,2,3,4,5]

But I don't think I fully understand why. Why is the return value of each the same array? Doesn't each just provide a method for iterating? Or is it just common practice for the each method to return the original value?

Answer

user166390 picture user166390 · Jul 22, 2012

Array#each returns the [array] object it was invoked upon: the result of the block is discarded. Thus if there are no icky side-effects to the original array then nothing will have changed.

Perhaps you mean to use map?

p [1,2,3,4,5].map { |i| i*i }

Related questions

Returning Multiple Values From Map

Is there a way to do: a = b.map{ |e| #return multiple elements to be added to a } Where rather than returning a single object for each iteration to be added to a, multiple objects can be returned. I'm currently …

Read More
How to check if a value exists in an array in Ruby

I have a value 'Dog' and an array ['Cat', 'Dog', 'Bird']. How do I check if it exists in the array without looping through it? Is there a simple way of checking if the value exists, nothing more?

Read More
What is the "right" way to iterate through an array in Ruby?

PHP, for all its warts, is pretty good on this count. There's no difference between an array and a hash (maybe I'm naive, but this seems obviously right to me), and to iterate through either you just do foreach (array/…

Read More