Explicit return statement in Ruby - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this Ruby method with explicit return?

Consider the following Ruby method. What will be printed when example_method is called?

Ruby

def example_method
  return 5
  10
end

puts example_method

A nil

B 10

C 5

D SyntaxError

💡 Hint

Remember that return immediately exits the method with the given value.

The return 5 line stops the method and returns 5. The line 10 is never reached.

❓ Predict Output

intermediate

What does this method return without an explicit return?

Look at this Ruby method. What value does it return when called?

Ruby

def no_return_method
  3 + 4
end

puts no_return_method

A SyntaxError

B 7

C 3 + 4

D nil

💡 Hint

In Ruby, the last evaluated expression is returned if no explicit return is used.

The method returns the result of 3 + 4, which is 7, because Ruby returns the last expression automatically.

🔧 Debug

advanced

Which option causes a syntax error due to incorrect return usage?

Identify which code snippet will cause a syntax error in Ruby because of incorrect use of return.

A

def test
  return 5 +
end

B

def test
  return
  puts 'Hello'
end

C

def test
  return 5
end

D

def test
  puts 'Hi'
  return 10
end

💡 Hint

Look for incomplete expressions after the return keyword.

Option A has an incomplete expression after return (5 +) causing a syntax error. Others are valid.

🧠 Conceptual

advanced

What is the effect of an explicit return inside a block?

What happens if you use return inside a block passed to a method in Ruby?

A It returns from the entire method that contains the block.

B It returns from the block only, continuing the method execution.

C It causes a syntax error because return is not allowed in blocks.

D It returns nil and continues execution.

💡 Hint

Think about how return behaves inside blocks versus methods.

In Ruby, a return inside a block returns from the method that contains the block, not just the block itself.

🚀 Application

expert

What is the output of this Ruby method with multiple returns?

Analyze this Ruby method and determine what it prints when called.

Ruby

def multi_return(x)
  if x > 10
    return 'Greater'
  elsif x == 10
    return 'Equal'
  end
  'Smaller'
end

puts multi_return(10)

A Greater

B Smaller

C nil

D Equal

💡 Hint

Check the condition that matches the input and which return is executed.

Since x is 10, the second condition matches and returns 'Equal'.

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