Why functional patterns complement OOP in Ruby - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a method that returns the square of a number.

Ruby

def square(num)
  num [1] num
end

Drag options to blanks, or click blank then click option'

A+

B*

C-

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Using '+' instead of '*' will add the number to itself, not square it.

The method multiplies the number by itself to get the square.

2fill in blank

medium

Complete the code to create an array of squares from 1 to 5 using map.

Ruby

squares = (1..5).[1] { |n| n * n }

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Amap

Beach

Cselect

Dreduce

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'each' returns the original array, not the transformed one.

The map method transforms each element by applying the block, returning a new array.

3fill in blank

hard

Fix the error in the code to filter even numbers from an array.

Ruby

evens = [1, 2, 3, 4, 5].[1] { |n| n.even? }

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Amap

Beach

Creduce

Dselect

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'map' returns transformed elements but does not filter.

The select method filters elements based on the block's condition.

4fill in blank

hard

Fill both blanks to create a hash of word lengths for words longer than 3 characters.

Ruby

lengths = words.select { |word| word.length > 3 }.map { |word| [ [1], [2] ] }.to_h

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Aword

Bword.length

Cword.size

Dword.upcase

Attempts:

3 left

💡 Hint

Common Mistakes

Using word.size is valid but not the expected answer here.

The hash keys are words, and the values are their lengths using word.length.

5fill in blank

hard

Fill all three blanks to create a hash of uppercase words and their lengths for words longer than 4 characters.

Ruby

result = words.select { |word| word.length [3] 4 }.map { |word| [ [1], [2] ] }.to_h

Drag options to blanks, or click blank then click option'

Aword.upcase

Bword.length

C>

Dword.downcase

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' instead of '>' will filter the wrong words.

The keys are uppercase words, values are their lengths, filtered by length greater than 4.