Enumerator Quiz

Learning Goal

Become familiar with using common iterators introduced in the previous lesson.

???

Challenge

?: Using .each

Let's try out the enumerator methods we just learned. Refer back to the previous lessons to help you pass this challenge. Below, we have a variable, lunch_menu, set equal to an Array of lunch menu items.

Since you're super-hungry and super-excited about lunch, use the .map method to enumerate over the Array and append an "!" ("exclamation mark") to each menu item.

lunch_menu = ["pizza", "sandwich", "sushi", "soup", "salad"]

Which piece of code will achieve the desired result?

( )

lunch_menu.reduce{|memo, item| memo << item }

(x)

lunch_menu.map{|item| "#{item}!" }

( )

lunch_menu.reduce{|item, memo| memo += item }

( )

lunch_menu.map{|item| (item, "!") }

?: Using .collect

Below we have a variable, nums, set equal to an Array of numbers. Enumerate over the Array and return a new Array of the squares of those numbers.

nums = [1, 2, 3, 4]

Which piece of code will achieve the desired result?

(x)

nums.collect { |n| n * n }

( )

nums.collect do |n|
  n + n
end

( )

nums.collect { |n| nn }

( )

nums.collect do |n|
  n
end

?: Using .select

Below we have a variable, odds_and_evens, set equal to an Array of numbers. Use the .select enumerator to iterate over the Array and return any even numbers. This requires checking if a number is even. If you're unsure how to do that, reference the Ruby Documentation for Integer or try a Google search!

odds_and_evens = [1, 3, 2, 18, 5, 10, 24]

Which piece of code will achieve the desired result?

( )

odds_and_evens.select do |n|
  n / 2
end

(x)

odds_and_evens.select do |n|
  n % 2 == 0
end

( )

odds_and_evens.select do |n|
  n.odd?
end

( )

odds_and_evens.select do |n|
  n + 2
end

?: Using .find

Below we once again have a variable, odds_and_evens, set equal to an Array of numbers. This time, use the .find method to iterate over the Array and return only the first Array element that is odd.

odds_and_evens = [2, 3, 2, 18, 5, 10, 24]

Which piece of code will achieve the desired result?

( )

odds_and_evens.find do |num|
  num.even?
end

( )

odds_and_evens.find do |num|
  num / 2
end

( )

odds_and_evens.find do |num|
  num
end

(x)

odds_and_evens.find do |num|
  num.odd?
end

?: Using include?

Below we have a variable, famous_cats, set equal to an Array of famous cats. Use the .include? method to check and see if the Array includes the string "Maru".

famous_cats = ["Maru", "Lil Bub", "Grumpy Cat"]

Which piece of code will achieve the desired result?

(x)

famous_cats.include?("Maru")

( )

famous_cats.include?

( )

famous_cats.include?(true)

???

View Enumerator Coding Challenge on Learn.co and start learning to code for free.