MCQs on Error Handling | Ruby

Learn the essential concepts of error handling in Ruby, including exceptions, the use of begin, rescue, and ensure blocks. These MCQs will help you understand Ruby’s error-handling mechanisms.

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1. Understanding Errors and Exceptions

1. In Ruby, which of the following is used to handle errors and exceptions?
   • A) try
   • B) handle
   • C) rescue
   • D) catch
2. What is the difference between an error and an exception in Ruby?
   • A) Errors are always critical, while exceptions are recoverable
   • B) Errors are recoverable, while exceptions are always fatal
   • C) Exceptions are more difficult to handle than errors
   • D) Errors and exceptions are the same in Ruby
3. Which class does all exceptions in Ruby inherit from?
   • A) Exception
   • B) Error
   • C) StandardError
   • D) RuntimeError
4. What is the default behavior when an exception is not caught in Ruby?
   • A) It prints an error message and continues execution
   • B) It stops the program execution
   • C) It logs the exception to a file
   • D) It ignores the exception silently
5. What type of exception is raised if a method is called with wrong arguments in Ruby?
   • A) NoMethodError
   • B) ArgumentError
   • C) TypeError
   • D) RuntimeError

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2. Using begin, rescue, and ensure

6. What is the purpose of the begin block in Ruby error handling?
   • A) To define the code that might raise an exception
   • B) To define the code to be executed after an exception is raised
   • C) To catch exceptions raised by other methods
   • D) To terminate the program if an error occurs
7. What does the rescue block do in Ruby?
   • A) It ensures that the code runs after the exception
   • B) It handles exceptions raised in the begin block
   • C) It prints a message when no exceptions occur
   • D) It raises a new exception after handling the old one
8. Which of the following is the correct syntax for rescuing an exception?
   • A) rescue => ExceptionType
   • B) rescue ExceptionType
   • C) begin rescue ExceptionType end
   • D) rescue from ExceptionType
9. What does the ensure block do in Ruby?
   • A) It runs the code only if an exception was raised
   • B) It runs the code after both begin and rescue
   • C) It runs only if the program has not executed successfully
   • D) It raises a new exception after handling the current one
10. In which order are begin, rescue, and ensure blocks executed in Ruby?
    • A) begin -> rescue -> ensure
    • B) begin -> ensure -> rescue
    • C) rescue -> begin -> ensure
    • D) ensure -> begin -> rescue

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3. Advanced Error Handling

11. What happens if an exception is raised inside the ensure block?
    • A) The program terminates without handling the exception
    • B) The exception is passed to the rescue block
    • C) The exception is ignored and the program continues
    • D) The exception is raised after ensure execution completes
12. Can the rescue block handle multiple types of exceptions in Ruby?
    • A) No, it can only handle one exception at a time
    • B) Yes, using multiple rescue blocks
    • C) Yes, by specifying multiple exceptions in a single rescue statement
    • D) No, each exception needs its own begin block
13. What happens if no exception is raised in the begin block?
    • A) The rescue block is executed
    • B) The ensure block is executed
    • C) The program stops without executing the ensure block
    • D) The program throws a NoExceptionError
14. What does rescue => e do in Ruby?
    • A) It assigns the exception to the variable e
    • B) It prints the exception message
    • C) It causes the program to terminate
    • D) It re-raises the exception
15. How can you re-raise an exception after handling it in the rescue block?
    • A) Using raise with no arguments
    • B) Using re_raise keyword
    • C) Using retry statement
    • D) Using throw

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4. Specific Exception Handling

16. Which of the following exception types is raised when an undefined method is called in Ruby?
    • A) NoMethodError
    • B) ArgumentError
    • C) NameError
    • D) RuntimeError
17. Which exception is raised when you attempt to divide by zero in Ruby?
    • A) ZeroDivisionError
    • B) ArgumentError
    • C) TypeError
    • D) StandardError
18. What is the correct syntax to handle a ZeroDivisionError exception in Ruby?
    • A) rescue ZeroDivisionError => e
    • B) rescue ZeroDivisionError
    • C) catch ZeroDivisionError
    • D) raise ZeroDivisionError
19. In Ruby, what is the class used for custom exception handling?
    • A) CustomError
    • B) StandardError
    • C) Exception
    • D) RuntimeError
20. How do you define a custom exception in Ruby?
    • A) class CustomError < StandardError; end
    • B) class CustomError < Exception; end
    • C) def CustomError; end
    • D) class CustomError: StandardError; end

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5. Practical Examples of Error Handling

21. Which block is executed regardless of whether an exception is raised or not?
    • A) rescue
    • B) ensure
    • C) catch
    • D) raise
22. Can you nest begin blocks in Ruby?
    • A) No, Ruby only allows a single begin block
    • B) Yes, but only one rescue block is allowed
    • C) Yes, you can nest multiple begin blocks
    • D) Yes, but only within the ensure block
23. What is the output when the following Ruby code is executed?

rubyCopy codebegin  
  raise "Error!"  
rescue => e  
  puts "Caught an exception: #{e.message}"  
end

• A) “Caught an exception: Error!”
• B) “Error!”
• C) nil
• D) “Caught an exception: Exception”

24. Which of the following would you use to retry a block of code after an exception?
    • A) retry
    • B) retry_block
    • C) repeat
    • D) catch
25. What is the difference between raise and fail in Ruby?
    • A) raise creates a new exception, while fail prints an error message
    • B) fail is an alias for raise
    • C) raise can only be used with begin, while fail cannot
    • D) There is no difference
26. Which exception class is the superclass for all Ruby exceptions?
    • A) Exception
    • B) StandardError
    • C) RuntimeError
    • D) NoMethodError
27. How would you raise a custom exception with a message in Ruby?
    • A) raise CustomError.new(“Error message”)
    • B) raise “Error message”
    • C) raise CustomError, “Error message”
    • D) Both A and C
28. Can exceptions be handled asynchronously in Ruby?
    • A) Yes, by using threads and rescue blocks
    • B) No, Ruby does not support asynchronous exception handling
    • C) Yes, but only with external libraries
    • D) No, exceptions must always be synchronous
29. What would happen if the ensure block has an exception raised in Ruby?
    • A) The exception is ignored
    • B) The program terminates immediately
    • C) The exception is raised after the ensure block completes
    • D) The program continues executing with no interruption
30. Which of the following is an example of handling multiple exceptions in a single rescue block?
    • A) rescue ZeroDivisionError, ArgumentError
    • B) rescue [ZeroDivisionError, ArgumentError]
    • C) rescue ZeroDivisionError then ArgumentError
    • D) Both A and B

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Answers Table:

Qno	Answer
1	C) rescue
2	A) Errors are always critical, while exceptions are recoverable
3	A) Exception
4	B) It stops the program execution
5	B) ArgumentError
6	A) To define the code that might raise an exception
7	B) It handles exceptions raised in the begin block
8	B) rescue ExceptionType
9	B) It runs the code after both begin and rescue
10	A) begin -> rescue -> ensure
11	A) The program terminates without handling the exception
12	C) Yes, by specifying multiple exceptions in a single rescue statement
13	B) The ensure block is executed
14	A) It assigns the exception to the variable e
15	A) Using raise with no arguments
16	A) NoMethodError
17	A) ZeroDivisionError
18	A) rescue ZeroDivisionError => e
19	C) Exception
20	A) class CustomError < StandardError; end
21	B) ensure
22	C) Yes, you can nest multiple begin blocks
23	A) “Caught an exception: Error!”
24	A) retry
25	B) fail is an alias for raise
26	A) Exception
27	D) Both A and C
28	A) Yes, by using threads and rescue blocks
29	C) The exception is raised after the ensure block completes
30	D) Both A and B