What is Ruby - Practice Questions & Exercises

Challenge - 5 Problems

🧠 Conceptual

intermediate

What is Ruby primarily used for?

Ruby is a popular programming language. What is its main use?

A Building web applications and scripting

B Designing hardware circuits

C Creating operating systems

D Editing videos and images

💡 Hint

Think about what Ruby is famous for in software development.

Ruby is mainly used for building web applications and scripting tasks. It is not used for hardware design, OS creation, or media editing.

❓ Predict Output

intermediate

What is the output of this Ruby code?

Look at the Ruby code below. What will it print?

Ruby

puts 'Hello, Ruby!'

A Hello, Ruby!

B hello, ruby!

C HELLO, RUBY!

D Error: undefined method 'puts'

💡 Hint

Remember Ruby is case-sensitive and 'puts' prints exactly what is inside the quotes.

The code prints the string exactly as it appears, including capitalization.

❓ Predict Output

advanced

What is the output of this Ruby method call?

Consider this Ruby code. What will it output?

Ruby

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

puts greet
puts greet('Alice')

A Error: wrong number of arguments

B

Hello, !
Hello, Alice!

C

Hello, friend!
Hello, friend!

D

Hello, friend!
Hello, Alice!

💡 Hint

Look at the default parameter in the method definition.

The method greet has a default argument 'friend'. Calling greet without arguments uses the default. Calling with 'Alice' uses that value.

🔧 Debug

advanced

What error does this Ruby code raise?

Look at this Ruby code snippet. What error will it cause?

Ruby

arr = [1, 2, 3]
puts arr[5]

A IndexError

B nil

C TypeError

D NoMethodError

💡 Hint

What happens when you access an array index that does not exist in Ruby?

Ruby returns nil when accessing an array index outside its range, no error is raised.

🧠 Conceptual

expert

Which feature is unique to Ruby compared to many other languages?

Ruby has many features. Which one below is a unique characteristic of Ruby?

A Does not support object-oriented programming

B Uses curly braces for blocks instead of do-end

C Everything is an object, even numbers and classes

D Requires explicit type declarations for variables

💡 Hint

Think about how Ruby treats data and code elements.

In Ruby, everything is an object, including numbers, classes, and even nil. This is different from many languages where primitives are not objects.

Practice

1. What is Ruby primarily known as?

easy

A. A type of database

B. A programming language

C. A web browser

D. An operating system

Solution

1. Step 1: Understand Ruby's category

   Ruby is a tool used to write instructions for computers, which means it is a programming language.

2. Step 2: Eliminate other options

   It is not a database, browser, or operating system, so those options are incorrect.

3. Final Answer:

   A programming language -> Option B

4. Quick Check:

   Ruby = programming language [OK]

Hint: Ruby is a language to tell computers what to do [OK]

Common Mistakes:

• Confusing Ruby with a database
• Thinking Ruby is software like a browser
• Mixing Ruby with operating systems

2. Which of the following is the correct way to print "Hello" in Ruby?

easy

A. print("Hello")

B. echo "Hello";

C. console.log("Hello")

D. printf("Hello")

Solution

1. Step 1: Identify Ruby's print syntax

   Ruby uses the method print() to show text on the screen.

2. Step 2: Check other options for language mismatch

   echo is from PHP, console.log is JavaScript, printf is C-style but less common in Ruby for simple output.

3. Final Answer:

   print("Hello") -> Option A

4. Quick Check:

   Ruby print syntax = print("Hello") [OK]

Hint: Ruby uses print() to show text [OK]

Common Mistakes:

• Using echo instead of print
• Using console.log from JavaScript
• Confusing printf with print

3. What will the following Ruby code output?

puts "Ruby" + " is fun"

medium

A. Ruby is fun

B. Ruby+ is fun

C. nuf si ybuR

D. Error

Solution

1. Step 1: Understand string concatenation in Ruby

   The + operator joins two strings together without extra characters.

2. Step 2: Understand puts output

   puts prints the string and adds a new line automatically, but the output shown is the text without showing the newline character.

3. Final Answer:

   Ruby is fun -> Option A

4. Quick Check:

   "Ruby" + " is fun" = "Ruby is fun" [OK]

Hint: Plus (+) joins strings in Ruby [OK]

Common Mistakes:

• Thinking + adds a plus sign
• Confusing puts with print
• Expecting an error from string addition

4. Find the error in this Ruby code:

puts "Hello World

medium

A. No error, code is correct

B. Missing parentheses after puts

C. puts should be capitalized

D. Missing closing double quote

Solution

1. Step 1: Check string syntax

   The string starts with a double quote but does not have a closing double quote.

2. Step 2: Verify other syntax parts

   Parentheses are optional in Ruby for puts, and puts is lowercase by convention, so no error there.

3. Final Answer:

   Missing closing double quote -> Option D

4. Quick Check:

   Unclosed string causes syntax error [OK]

Hint: Always close your quotes in strings [OK]

Common Mistakes:

• Forgetting to close quotes
• Thinking parentheses are mandatory
• Capitalizing puts incorrectly

5. You want to create a simple Ruby program that prints each word from an array on a new line. Which code correctly does this?

hard

A. words = ("Ruby", "is", "fun")
for word in words puts word end

B. words = ["Ruby", "is", "fun"]
print words.join("\n")

C. words = ["Ruby", "is", "fun"]
words.each { |word| puts word }

D. words = {"Ruby", "is", "fun"}
words.each do |word|
print word
end

Solution

1. Step 1: Identify correct array syntax

   words = ["Ruby", "is", "fun"] words.each { |word| puts word } uses square brackets [] to create an array, which is correct in Ruby.

2. Step 2: Check iteration and printing method

   words = ["Ruby", "is", "fun"] words.each { |word| puts word } uses each with a block and puts to print each word on a new line, which is the correct approach.

3. Final Answer:

   words = ["Ruby", "is", "fun"]\nwords.each { |word| puts word } -> Option C

4. Quick Check:

   Array + each + puts = print words line by line [OK]

Hint: Use array.each with puts to print each item [OK]

Common Mistakes:

• Using parentheses instead of brackets for arrays
• Using print instead of puts for new lines
• Using curly braces for arrays