Range operators (.. and ...) in Ruby - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a range from 1 to 5 inclusive.

Ruby

range = 1 [1] 5
puts range.to_a

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

A..

B...

C+

D-

Attempts:

3 left

💡 Hint

Common Mistakes

Using the exclusive range operator (...) which excludes the last number.

Using arithmetic operators like + or - instead of range operators.

The .. operator creates a range including the end value.

2fill in blank

medium

Complete the code to create a range from 1 to 5 excluding 5.

Ruby

range = 1 [1] 5
puts range.to_a

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

A..

B...

C-

D+

Attempts:

3 left

💡 Hint

Common Mistakes

Using the inclusive range operator (..) which includes the last number.

Using arithmetic operators like + or - instead of range operators.

The ... operator creates a range excluding the end value.

3fill in blank

hard

Fix the error in the code to create a range from 'a' to 'e' inclusive.

Ruby

letters = 'a' [1] 'e'
puts letters.to_a

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

A..

B+

C-

D...

Attempts:

3 left

💡 Hint

Common Mistakes

Using the exclusive range operator (...) which excludes the last letter.

Using arithmetic operators instead of range operators.

Use the inclusive range operator .. to include 'e' in the range.

4fill in blank

hard

Fill both blanks to create a range from 10 to 20 excluding 20 and print its array.

Ruby

range = 10 [1] 20
puts range.[2].to_a

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

A...

B..

Cto_a

Dto_s

Attempts:

3 left

💡 Hint

Common Mistakes

Using inclusive range operator (..) which includes 20.

Using to_s instead of to_a to convert the range.

Use the exclusive range operator ... to exclude 20, and to_a to convert the range to an array.

5fill in blank

hard

Fill all three blanks to create a range from 'm' to 'r' inclusive, convert it to an array, and print it.

Ruby

letters = 'm' [1] 'r'
array = letters.[2]
puts array.[3]

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

A..

Bto_a

Cjoin

D...

Attempts:

3 left

💡 Hint

Common Mistakes

Using exclusive range operator (...) which excludes 'r'.

Forgetting to convert the range to an array before joining.

Using puts directly on the range without conversion.

Use .. for inclusive range, to_a to convert to array, and join to print as a string.

Practice

1. What is the main difference between the Ruby range operators .. and ...?

easy

A. .. includes the end value, ... excludes the end value

B. .. excludes the end value, ... includes the end value

C. .. creates an array, ... creates a hash

D. .. is used for strings only, ... is used for numbers only

Solution

1. Step 1: Understand the .. operator

   The .. operator creates a range that includes the last value in the sequence.

2. Step 2: Understand the ... operator

   The ... operator creates a range that excludes the last value, stopping just before it.

3. Final Answer:

   .. includes the end value, ... excludes the end value -> Option A

4. Quick Check:

   Range inclusion = .., exclusion = ... [OK]

Hint: Remember: two dots include, three dots exclude end [OK]

Common Mistakes:

• Confusing which operator includes or excludes the end
• Thinking both operators behave the same
• Assuming ranges create arrays automatically
• Mixing up usage with different data types

2. Which of the following is the correct syntax to create a range from 1 to 5, excluding 5, in Ruby?

easy

A. range = 1..5

B. range = 1...5

C. range = (1..5).exclude_end?

D. range = 1-5

Solution

1. Step 1: Identify the operator for excluding the end

   The ... operator excludes the end value, so 1...5 means 1, 2, 3, 4.

2. Step 2: Check other options

   1..5 includes 5, (1..5).exclude_end? is a method call, not range creation, and 1-5 is subtraction.

3. Final Answer:

   range = 1...5 -> Option B

4. Quick Check:

   Exclude end uses three dots ... [OK]

Hint: Use three dots to exclude the last number [OK]

Common Mistakes:

• Using two dots when exclusion is needed
• Confusing method calls with range syntax
• Using subtraction instead of range
• Forgetting parentheses for method calls

3. What will be the output of the following Ruby code?

puts (1..3).to_a.inspect
puts (1...3).to_a.inspect

medium

A. [1, 2]
[1, 2]

B. [1, 2]
[1, 2, 3]

C. [1, 2, 3]
[1, 2, 3]

D. [1, 2, 3]
[1, 2]

Solution

1. Step 1: Convert (1..3) to array

   The range 1..3 includes 3, so (1..3).to_a is [1, 2, 3].

2. Step 2: Convert (1...3) to array

   The range 1...3 excludes 3, so (1...3).to_a is [1, 2].

3. Final Answer:

   [1, 2, 3] [1, 2] -> Option D

4. Quick Check:

   Two dots include end, three dots exclude end [OK]

Hint: Remember to_a shows all included values in the range [OK]

Common Mistakes:

• Assuming both ranges include the end
• Mixing up which operator excludes the end
• Forgetting to convert range to array for output
• Misreading the output format

4. The following Ruby code is intended to print numbers from 1 to 5, excluding 5. What is the error?

for i in 1..5
  puts i
end

medium

A. The for loop syntax is incorrect

B. The loop variable i is not defined

C. The range should use ... to exclude 5

D. The puts statement should be outside the loop

Solution

1. Step 1: Analyze the range used in the loop

   The range 1..5 includes 5, so the loop prints 1 through 5.

2. Step 2: Identify how to exclude 5

   To exclude 5, use the ... operator: 1...5 which stops before 5.

3. Final Answer:

   The range should use ... to exclude 5 -> Option C

4. Quick Check:

   Exclude end with three dots ... [OK]

Hint: Use three dots to exclude the last number in loops [OK]

Common Mistakes:

• Using two dots when exclusion is needed
• Thinking loop variable needs declaration
• Misunderstanding for loop syntax in Ruby
• Placing puts outside the loop incorrectly

5. You want to create a Ruby method that returns all numbers from 1 up to but not including a given number n. Which range operator should you use inside the method to achieve this?

hard

A. Use 1...n to exclude n

B. Use 1...n-1 to exclude n and n-1

C. Use 1...(n+1) to exclude n

D. Use 1..n to include n

Solution

1. Step 1: Understand the requirement

   The method should return numbers from 1 up to but not including n.

2. Step 2: Choose the correct range operator

   Using 1...n creates a range that excludes n, exactly what is needed.

3. Step 3: Evaluate other options

   1..n includes n, 1...(n+1) includes n, 1...n-1 excludes n-1 too, which is incorrect.

4. Final Answer:

   Use 1...n to exclude n -> Option A

5. Quick Check:

   Three dots exclude the end value [OK]

Hint: Use three dots to exclude the upper limit without math [OK]

Common Mistakes:

• Using two dots and including the end value
• Subtracting 1 manually instead of using three dots
• Misplacing parentheses causing wrong range
• Using three dots with arithmetic causing off-by-one