String interpolation with #{} in Ruby - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of string interpolation with variables

What is the output of this Ruby code?

Ruby

name = "Alice"
age = 30
puts "My name is #{name} and I am #{age} years old."

A My name is Alice and I am 30 years old.

B My name is Alice and I am #{age} years old.

C My name is name and I am age years old.

D My name is #{name} and I am #{age} years old.

💡 Hint

Remember that #{variable} inside double quotes evaluates the variable's value.

In Ruby, string interpolation with #{variable} inside double quotes replaces the expression with the variable's value.

❓ Predict Output

intermediate

Interpolation with expressions inside #{}

What will this Ruby code print?

Ruby

a = 5
b = 3
puts "Sum is #{a + b} and product is #{a * b}."

A Sum is #{a + b} and product is #{a * b}.

B Sum is a + b and product is a * b.

C Sum is 8 and product is 15.

D Sum is 53 and product is 15.

💡 Hint

Inside #{}, Ruby evaluates the expression before converting to string.

Ruby evaluates expressions inside #{}, so a + b becomes 8 and a * b becomes 15.

🔧 Debug

advanced

Identify the error in string interpolation

What error does this Ruby code produce?

Ruby

name = "Bob"
puts 'Hello, #{name}!'

A Hello, #{name}!

B Hello, Bob!

C SyntaxError

D NameError

💡 Hint

Check the type of quotes used for string interpolation.

Single quotes in Ruby do not process #{}, so the output is the literal string with #{name}.

❓ Predict Output

advanced

Complex interpolation with method call

What is the output of this Ruby code?

Ruby

def greet(name)
  "Hello, #{name.upcase}!"
end
puts greet("eve")

A Hello, #{name.upcase}!

B Hello, eve!

C NoMethodError

D Hello, EVE!

💡 Hint

Inside #{}, you can call methods on variables.

The method upcase converts the string to uppercase before interpolation.

🧠 Conceptual

expert

Why does this interpolation fail?

Consider this Ruby code: ```ruby number = 10 puts "Value: #{number + '5'}" ``` What error will this code raise and why?

A SyntaxError due to invalid interpolation syntax

B TypeError because you cannot add Integer and String

C NameError because 'number' is undefined

D No error, outputs: Value: 105

💡 Hint

Check the types of operands inside the interpolation expression.

Ruby cannot add an Integer (number) and a String ('5'), causing a TypeError.