Array slicing and ranges in Ruby - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this Ruby code using range slicing?

Consider the following Ruby code snippet. What will be printed?

Ruby

arr = [10, 20, 30, 40, 50]
puts arr[1..3].inspect

A [20, 30, 40, 50]

B [20, 30, 40]

C [10, 20, 30]

D [30, 40, 50]

💡 Hint

Remember that the range 1..3 includes elements at index 1, 2, and 3.

The range 1..3 selects elements starting at index 1 up to and including index 3. So arr[1..3] returns [20, 30, 40].

❓ Predict Output

intermediate

What does this code output when slicing with an exclusive range?

Look at this Ruby code. What will it print?

Ruby

arr = ['a', 'b', 'c', 'd', 'e']
puts arr[0...3].inspect

A ["b", "c", "d"]

B ["a", "b", "c", "d"]

C ["a", "b", "c"]

D ["a", "b"]

💡 Hint

The three dots in the range exclude the last index.

The range 0...3 includes indices 0, 1, and 2 but excludes 3. So arr[0...3] returns ["a", "b", "c"].

❓ Predict Output

advanced

What is the output of this code using negative indices in slicing?

Analyze this Ruby code and determine its output.

Ruby

arr = [1, 2, 3, 4, 5, 6]
puts arr[-4..-2].inspect

A [3, 4, 5]

B [4, 5, 6]

C [2, 3, 4]

D [3, 4]

💡 Hint

Negative indices count from the end: -1 is last element.

Index -4 corresponds to element 3, -2 corresponds to element 5. The range -4..-2 includes indices -4, -3, -2, so elements [3, 4, 5].

❓ Predict Output

advanced

What error does this Ruby code raise when slicing with an invalid range?

What happens when you run this Ruby code?

Ruby

arr = [7, 8, 9]
puts arr[5..7].inspect

A ArgumentError

B nil

C IndexError

D []

💡 Hint

Check what Ruby returns when slicing beyond array length.

Ruby returns nil when the start index of the range is beyond the array length. So arr[5..7] returns nil, not an error or empty array.

🧠 Conceptual

expert

How many elements are in the resulting array after this slicing?

Given this Ruby code, how many elements does the resulting array have?

Ruby

arr = (1..10).to_a
result = arr[2..8]
puts result.size

A 7

B 6

C 8

D 9

💡 Hint

Remember that the range 2..8 includes both ends.

The slice arr[2..8] includes elements at indices 2 through 8, which is 7 elements total.