Each as the primary iterator in Ruby - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the each method do in Ruby?

The each method goes through each item in a collection like an array or hash, one by one, and runs the code inside the block for each item.

beginner

How do you write a simple each loop for an array [1, 2, 3]?

You write: <br>

[1, 2, 3].each do |number|
  puts number
end

This prints each number on its own line.

intermediate

Can each be used with hashes? How?

Yes! You can use each with hashes to get both key and value. For example:<br>

{a: 1, b: 2}.each do |key, value|
  puts "#{key}: #{value}"
end

intermediate

What is the return value of each?

The each method returns the original collection it was called on, unchanged.

beginner

Why is each called the primary iterator in Ruby?

Because each is the most common and basic way to loop through collections in Ruby. Many other methods build on or use each internally.

What does the each method yield to the block when used on an array?

A The entire array

B The index of each element

C Nothing

D Each element of the array

The each method passes each element of the array one by one to the block.

What will this code print?<br>

["a", "b", "c"].each { |x| puts x.upcase }

A A B C

B a b c

C abc

D Error

The code prints each letter in uppercase on its own line: A B C.

When using each on a hash, what does the block receive?

A Both key and value as two block parameters

B Only the values

C Only the keys

D An array of keys

The block receives two parameters: the key and the value for each pair.

What does each return after finishing iteration?

A The last element processed

B The original collection

C nil

D The number of elements

each always returns the original collection it was called on.

Which of these is true about each in Ruby?

A It modifies the original collection

B It returns a new array

C It is the primary iterator method

D It only works with arrays

each is the primary iterator because it is the basic way to loop through collections.

Explain how the each method works in Ruby and give an example with an array.

Think about how you tell Ruby to do something for every item in a list.

Describe how you use each with a hash and what the block receives.

Remember a hash has pairs, so the block gets two things.