Method declaration with def in Ruby - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of a simple method call

What is the output of this Ruby code?

Ruby

def greet(name)
  "Hello, #{name}!"
end

puts greet("Alice")

A greet

B Hello, Alice!

C Hello, name!

D nil

💡 Hint

Look at how the method uses string interpolation with the parameter.

The method greet takes a name and returns a greeting string with that name inserted. Calling puts on the method call prints the greeting.

❓ Predict Output

intermediate

Return value of method without explicit return

What does this Ruby method return when called with argument 5?

Ruby

def square(x)
  x * x
end

result = square(5)
puts result

A SyntaxError

B 5

C nil

D 25

💡 Hint

In Ruby, the last evaluated expression is returned by default.

The method multiplies x by itself and returns the result. Calling square(5) returns 25.

🔧 Debug

advanced

Identify the error in method declaration

What error does this Ruby code produce?

Ruby

def add_numbers(a, b)
  sum = a + b
  puts sum
end

add_numbers(3, 4)

A No error, outputs 7

B NoMethodError: undefined method 'add_numbers'

C TypeError: no implicit conversion of nil into Integer

D SyntaxError: unexpected end-of-input, expecting keyword_end

💡 Hint

Check if all method definitions are properly closed.

The method is missing the 'end' keyword to close the definition, causing a syntax error.

❓ Predict Output

advanced

Method with default parameter value

What is the output of this Ruby code?

Ruby

def greet(name = "Guest")
  "Welcome, #{name}!"
end

puts greet
puts greet("Bob")

A

Welcome, Guest!
Welcome, Bob!

B

Welcome, !
Welcome, Bob!

C

Welcome, Guest!
Welcome, Guest!

D SyntaxError

💡 Hint

Look at the default value assigned to the parameter.

If no argument is given, the method uses the default 'Guest'. Otherwise, it uses the provided name.

🧠 Conceptual

expert

Understanding method scope and variable visibility

Consider this Ruby code. What is the output?

Ruby

def change_var(x)
  x = 10
end

value = 5
change_var(value)
puts value

A nil

B 10

C 5

D NameError

💡 Hint

Think about whether the method changes the original variable or just a copy.

The method changes only the local copy of x, not the original variable 'value'. So 'value' remains 5.