Explicit return statement in Ruby - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to explicitly return the sum of two numbers.

Ruby

def add(a, b)
  [1] a + b
end

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

Aputs

Bprint

Creturn

Dyield

Attempts:

3 left

💡 Hint

Common Mistakes

Using print or puts instead of return, which only outputs but does not return a value.

The return keyword explicitly sends the result back from the method.

2fill in blank

medium

Complete the code to explicitly return the string 'Hello' from the method.

Ruby

def greet
  [1] "Hello"
end

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

Aprint

Breturn

Cputs

Dyield

Attempts:

3 left

💡 Hint

Common Mistakes

Using puts or print which only display output but do not return a value.

The return keyword explicitly returns the string from the method.

3fill in blank

hard

Fix the error in the method to explicitly return the product of two numbers.

Ruby

def multiply(x, y)
  product = x * y
  [1] product
end

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

Aputs

Byield

Cprint

Dreturn

Attempts:

3 left

💡 Hint

Common Mistakes

Using puts or print which only output the value but do not return it.

Using return explicitly sends the product back from the method.

4fill in blank

hard

Fill both blanks to explicitly return the length of the string if it is greater than 5.

Ruby

def check_length(str)
  if str.length > 5
    [1] str.length
  else
    [2] 0
  end
end

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

Areturn

Bputs

Cprint

Dyield

Attempts:

3 left

💡 Hint

Common Mistakes

Using puts or print which only display output but do not return a value.

Both branches use return to explicitly send back a value from the method.

5fill in blank

hard

Fill all three blanks to explicitly return a hash with keys as uppercase letters and values as their lengths for words longer than 3 letters.

Ruby

def word_lengths(words)
  result = {}
  words.each do |word|
    if word.length > 3
      result[[1]] = [2]
      [3] result
    end
  end
  result
end

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

Aword.upcase

Bword.length

Creturn

Dword.downcase

Attempts:

3 left

💡 Hint

Common Mistakes

Using word.downcase instead of word.upcase for the key.

Not using return to explicitly return the hash inside the loop.

The method returns a hash where keys are uppercase words and values are their lengths. The return keyword explicitly returns the hash inside the loop.

Practice

1. What does the return keyword do in a Ruby method?

easy

A. It prints a value to the screen.

B. It immediately sends a value back and stops the method.

C. It creates a new variable inside the method.

D. It pauses the method without returning a value.

Solution

1. Step 1: Understand the purpose of return

   The return keyword in Ruby is used to send a value back from a method immediately.

2. Step 2: Recognize method behavior with return

   When Ruby sees return, it stops running the method and gives back the specified value.

3. Final Answer:

   It immediately sends a value back and stops the method. -> Option B

4. Quick Check:

   Explicit return stops method and returns value = B [OK]

Hint: Return sends value back and stops method immediately [OK]

Common Mistakes:

• Thinking return prints output
• Confusing return with variable creation
• Believing return pauses without returning

2. Which of the following is the correct way to explicitly return the value 10 from a Ruby method?

easy

A. return10

B. return = 10

C. return: 10

D. return(10)

Solution

1. Step 1: Check Ruby syntax for return

   Ruby allows return with or without parentheses, so return(10) is correct syntax.

2. Step 2: Identify invalid options

   return10 lacks space (syntax error), return = 10 is invalid assignment, and return: 10 uses wrong colon syntax.

3. Final Answer:

   return(10) -> Option D

4. Quick Check:

   Correct explicit return syntax = C [OK]

Hint: Use return with parentheses for explicit clarity [OK]

Common Mistakes:

• Using assignment syntax with return
• Using colon instead of parentheses
• Omitting parentheses but expecting error

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

def example
  return 5
  10
end

puts example

medium

A. 5

B. 10

C. nil

D. SyntaxError

Solution

1. Step 1: Analyze the method example

   The method first executes return 5, which immediately stops the method and returns 5.

2. Step 2: Understand unreachable code

   The line 10 after the return is never reached or executed.

3. Final Answer:

   5 -> Option A

4. Quick Check:

   Return stops method early, output = 5 [OK]

Hint: Return stops method; code after return is ignored [OK]

Common Mistakes:

• Thinking code after return runs
• Expecting last line value as output
• Confusing return with print

4. Identify the error in this Ruby method:

def check_number(num)
  if num > 0
    return 'Positive'
  else
    'Negative'
  end
  return
end

medium

A. The method has unreachable code after return.

B. The return keyword is used incorrectly inside if.

C. The else block should use return explicitly.

D. The method returns nil for negative numbers.

Solution

1. Step 1: Trace the if branch

   If num > 0, return 'Positive' exits the method immediately.

2. Step 2: Trace the else branch

   Else block evaluates 'Negative' as last expression (implicit return).

3. Step 3: Check post-conditional code

   The final return (nil) is unreachable as if-else covers all paths.

4. Final Answer:

   The method has unreachable code after return. -> Option A

5. Quick Check:

   Complete if-else leads to unreachable code [OK]

Hint: Check all paths return a value explicitly [OK]

Common Mistakes:

• Assuming last return runs always
• Thinking return inside if is wrong
• Ignoring implicit returns

5. You want a method that returns the first even number from an array or nil if none found. Which code correctly uses explicit return to stop early?

def first_even(numbers)
  numbers.each do |n|
    if n.even?
      return n
    end
  end
  nil
end

hard

A. Returns nil always because return is inside loop.

B. Returns all even numbers as an array.

C. Returns first even number or nil, stops early with return.

D. Raises error because return cannot be used in block.

Solution

1. Step 1: Understand method logic

   The method loops over each number and checks if it is even.

2. Step 2: Analyze explicit return usage

   When it finds an even number, it uses return n to immediately return that number and stop the method.

3. Step 3: Check fallback return

   If no even number is found, the method returns nil after the loop.

4. Final Answer:

   Returns first even number or nil, stops early with return. -> Option C

5. Quick Check:

   Explicit return stops loop and returns value early = A [OK]

Hint: Use return inside loop to exit method early when condition met [OK]

Common Mistakes:

• Thinking return inside block causes error
• Expecting all even numbers returned
• Ignoring nil fallback return