Each for iteration in Ruby - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the each method do in Ruby?

The each method goes through every 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 to print all elements in 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.

beginner

What is the role of the block variable in an each loop?

The block variable (like |item|) temporarily holds the current element from the collection during each loop cycle, so you can use it inside the block.

intermediate

Can each be used with hashes? How?

Yes! When used with a hash, each passes two block variables: the key and the value. For example: <br>

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

intermediate

What does the each method return after finishing the iteration?

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

What does the each method do in Ruby?

A Iterates over each element in a collection and runs a block of code

B Deletes elements from a collection

C Sorts the elements in a collection

D Creates a new collection with modified elements

The each method goes through each element and runs the given block for it.

How do you access the current element inside an each block?

A Using a method called <code>current</code>

B Using a global variable

C You cannot access it

D Using a block variable like <code>|item|</code>

The block variable holds the current element during each iteration.

What does each return after running?

A The last element

B The original collection

C The number of elements

D A new array with results

each returns the original collection unchanged.

Which of these is a correct way to use each with a hash?

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

B {a: 1, b: 2}.each do |item| puts item end

C {a: 1, b: 2}.each { puts key }

D {a: 1, b: 2}.each { |value| puts value }

When iterating a hash, you use two block variables for key and value.

What will this code print? <br>

 ["apple", "banana"].each do |fruit| puts fruit.upcase end 

A apple banana

B Error

C APPLE BANANA (each on new line)

D Nothing

The code prints each fruit in uppercase on its own line.

Explain how the each method works in Ruby and how you use it with arrays.

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

Describe how to use each with a hash and what block variables you need.

Remember a hash has pairs, so you need two variables.