Each for iteration in Ruby - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of each with array iteration

What is the output of this Ruby code?

Ruby

arr = [1, 2, 3]
result = []
arr.each { |x| result << x * 2 }
puts result.inspect

A [1, 2, 3]

B nil

C [2, 4, 6]

D [1, 4, 9]

💡 Hint

Remember that each iterates over elements and you can push transformed values into another array.

The each method goes through each element in arr. For each element x, it multiplies by 2 and appends to result. So result becomes [2, 4, 6].

❓ Predict Output

intermediate

Return value of each method

What does the following Ruby code print?

Ruby

numbers = [10, 20, 30]
result = numbers.each { |n| n + 5 }
puts result.inspect

A [15, 25, 35]

B [10, 20, 30]

C TypeError

D nil

💡 Hint

The each method returns the original array, not the transformed values.

The each method returns the original array it was called on, ignoring the block's return values. So result is [10, 20, 30].

🔧 Debug

advanced

Spot the error in each iteration

Which option will raise an error when trying to print each fruit in uppercase?

Ruby

fruits = ['apple', 'banana', 'cherry']
fruits.each do |fruit|
  puts fruit.upcase
end

A

fruits.each do |fruit|
  puts fruit.uppercase
end

B fruits.each { |fruit| puts fruit.upcase }

C

fruits.each do |fruit|
  puts fruit.upcase()
end

D

fruits.each do |f|
  puts f.upcase
end

💡 Hint

Check the method name for converting string to uppercase.

The method 'uppercase' does not exist in Ruby String class, so option A causes NoMethodError. The original code is correct and runs without error. Options B, C, and D are valid and produce output. Only A causes error.

📝 Syntax

advanced

Identify the syntax error in each block

Which option contains a syntax error in the each iteration?

Ruby

items = [1, 2, 3]

A

items.each do |item|
  puts item
end

B items.each do |item| puts item end

C items.each { |item| puts item }

D items.each |item| { puts item }

💡 Hint

Check the placement of pipes and braces in each block syntax.

Option D is invalid syntax because the pipes |item| must be inside the block delimiters {} or do..end. The correct syntax is either items.each { |item| ... } or items.each do |item| ... end.

🚀 Application

expert

Count elements with each iteration

Using each, how many elements in the array are greater than 5?

Ruby

arr = [3, 7, 2, 9, 5]
count = 0
arr.each do |x|
  count += 1 if x > 5
end
puts count

A 2

B 3

C 4

D 5

💡 Hint

Check each number and count only those greater than 5.

Only 7 and 9 are greater than 5, so count is 2.