Upto and downto methods in Ruby - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of using upto method

What is the output of the following Ruby code?

Ruby

result = []
5.upto(7) { |i| result << i }
puts result.join(",")

A 5,6,7

B 7,6,5

C 5,7

D 6,7

💡 Hint

Remember, upto counts from the starting number up to the ending number, including both.

The upto method starts at 5 and counts up to 7, including both 5 and 7, so the array contains 5, 6, and 7.

❓ Predict Output

intermediate

Output of using downto method

What will this Ruby code print?

Ruby

result = []
3.downto(1) { |i| result << i }
puts result.join("-")

A 1-2-3

B 3-2-1

C 3-1

D 2-1

💡 Hint

Downto counts down from the starting number to the ending number, including both.

The downto method starts at 3 and counts down to 1, so the array contains 3, 2, and 1.

🧠 Conceptual

advanced

Understanding return values of upto and downto

What is the return value of the following Ruby code snippet? ```ruby result = 1.upto(3) { |i| puts i } puts result ```

A

1
2
3
nil

B

1
2
3
3

C

1
2
3
1

D

1
2
3
Enumerator

💡 Hint

The upto method returns the receiver after iteration.

The upto method returns the starting number (receiver) after executing the block, so result is 1. But the code prints result, which is 1, after printing 1, 2, 3 inside the block.

❓ Predict Output

advanced

Output of combined upto and downto

What is the output of this Ruby code?

Ruby

output = []
2.upto(3) { |i| output << i }
3.downto(2) { |i| output << i }
puts output.join(",")

A 2,3,3,2

B 2,3,2,3

C 3,2,2,3

D 3,2,3,2

💡 Hint

The first loop counts up from 2 to 3, the second counts down from 3 to 2.

The first loop adds 2 and 3, the second adds 3 and 2, so the array is [2,3,3,2].

❓ Predict Output

expert

Counting iterations with upto and downto

How many times will the block run in this Ruby code?

Ruby

count = 0
10.downto(7) { count += 1 }
puts count

A 3

B 10

C 7

D 4

💡 Hint

Count how many numbers are between 10 and 7, including both.

The downto method runs the block for 10, 9, 8, and 7, so 4 times.