Multiple rescue clauses in Ruby - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to rescue a ZeroDivisionError.

Ruby

begin
  result = 10 / 0
rescue [1]
  puts "Cannot divide by zero"
end

Drag options to blanks, or click blank then click option'

AZeroDivisionError

BTypeError

CNameError

DArgumentError

Attempts:

3 left

💡 Hint

Common Mistakes

Using a wrong error class like TypeError or NameError.

Not rescuing any error and letting the program crash.

The ZeroDivisionError is raised when dividing by zero. Rescuing it handles this specific error.

2fill in blank

medium

Complete the code to rescue an IOError.

Ruby

begin
  file = File.open(__FILE__)
  file.close
  file.read
rescue [1]
  puts "IO operation failed"
end

Drag options to blanks, or click blank then click option'

AZeroDivisionError

BIOError

CRuntimeError

DNoMethodError

Attempts:

3 left

💡 Hint

Common Mistakes

Using unrelated error classes like ZeroDivisionError.

Not rescuing the correct error causes the program to crash.

IOError is raised for input/output errors like attempting to read from a closed file.

3fill in blank

hard

Fix the error in the rescue clause to handle both ZeroDivisionError and IOError.

Ruby

begin
  # some code that may raise errors
rescue [1], IOError
  puts "Handled an error"
end

Drag options to blanks, or click blank then click option'

AStandardError

BRuntimeError

CZeroDivisionError

DException

Attempts:

3 left

💡 Hint

Common Mistakes

Using a generic error like RuntimeError which may not catch the specific error.

Using Exception which is too broad and not recommended.

To rescue multiple errors, list them separated by commas. Here, ZeroDivisionError and IOError are rescued.

4fill in blank

hard

Fill both blanks to rescue ArgumentError and NoMethodError separately.

Ruby

begin
  # risky code
rescue [1]
  puts "Argument error caught"
rescue [2]
  puts "No method error caught"
end

Drag options to blanks, or click blank then click option'

AArgumentError

BZeroDivisionError

CNoMethodError

DIOError

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up error classes in rescue clauses.

Using the same error class for both rescue clauses.

Each rescue clause handles a specific error: ArgumentError and NoMethodError.

5fill in blank

hard

Fill all three blanks to rescue RuntimeError, TypeError, and StandardError in one rescue clause.

Ruby

begin
  # code that may raise errors
rescue [1], [2], [3]
  puts "An error was rescued"
end

Drag options to blanks, or click blank then click option'

ARuntimeError

BTypeError

CStandardError

DNoMethodError

Attempts:

3 left

💡 Hint

Common Mistakes

Using unrelated error classes like NoMethodError here.

Trying to rescue errors in separate rescue clauses instead of one.

Multiple errors can be rescued by listing them separated by commas in one rescue clause.

Practice

1. What is the purpose of using multiple rescue clauses in Ruby?

easy

A. To repeat the same error handling multiple times

B. To run code only when no errors occur

C. To handle different types of errors with specific responses

D. To skip error handling entirely

Solution

1. Step 1: Understand rescue clauses

   Multiple rescue clauses allow you to catch different error types separately.

2. Step 2: Purpose of specific error handling

   This helps you respond differently depending on the error type.

3. Final Answer:

   To handle different types of errors with specific responses -> Option C

4. Quick Check:

   Multiple rescue clauses = specific error handling [OK]

Hint: Multiple rescue clauses catch different errors separately [OK]

Common Mistakes:

• Thinking rescue clauses run only when no errors occur
• Assuming multiple rescue repeats same handling
• Believing rescue skips error handling

2. Which of the following is the correct syntax for multiple rescue clauses in Ruby?

easy

A. try
# code
rescue ZeroDivisionError
# handle zero division
rescue StandardError
# handle other errors
end

B. begin
# code
catch ZeroDivisionError
# handle zero division
catch StandardError
# handle other errors
end

C. begin
# code
rescue ZeroDivisionError, StandardError
# handle errors
end

D. begin
# code
rescue ZeroDivisionError
# handle zero division
rescue StandardError
# handle other errors
end

Solution

1. Step 1: Identify Ruby error handling syntax

   Ruby uses begin and rescue for error handling, not try or catch.

2. Step 2: Check multiple rescue clauses

   Multiple rescue clauses are written one after another inside begin...end.

3. Final Answer:

   begin # code rescue ZeroDivisionError # handle zero division rescue StandardError # handle other errors end -> Option D

4. Quick Check:

   Ruby uses begin-rescue-end with multiple rescue [OK]

Hint: Use begin-rescue-end blocks for multiple error types [OK]

Common Mistakes:

• Using try or catch instead of rescue
• Combining errors in one rescue without comma
• Incorrect block keywords

3. What will be the output of this Ruby code?

begin
  1 / 0
rescue ZeroDivisionError
  puts 'Zero division error caught'
rescue StandardError
  puts 'Standard error caught'
end

medium

A. Zero division error caught

B. Standard error caught

C. No output, program crashes

D. SyntaxError

Solution

1. Step 1: Identify the error raised

   The code 1 / 0 raises a ZeroDivisionError.

2. Step 2: Match error with rescue clauses

   The first rescue clause catches ZeroDivisionError and prints the message.

3. Final Answer:

   Zero division error caught -> Option A

4. Quick Check:

   ZeroDivisionError triggers first rescue [OK]

Hint: Match error type to first rescue clause that fits [OK]

Common Mistakes:

• Assuming StandardError rescue runs first
• Thinking program crashes without rescue
• Confusing syntax error with runtime error

4. Identify the error in this Ruby code with multiple rescue clauses:

begin
  puts 'Start'
rescue
  puts 'Rescue block'
rescue ZeroDivisionError
  puts 'Zero division error'
end

medium

A. Missing ensure block causes error

B. Multiple rescue clauses after a generic rescue cause syntax error

C. No error, code runs fine

D. Rescue clauses must be inside methods only

Solution

1. Step 1: Check for syntax errors

   In Ruby, a generic rescue clause must come after all specific rescue clauses. Placing a generic rescue before specific ones causes a syntax error.

2. Step 2: Analyze the code

   The code places a generic rescue first, then a specific rescue, which is invalid syntax.

3. Final Answer:

   Multiple rescue clauses after a generic rescue cause syntax error -> Option B

4. Quick Check:

   Generic rescue must be last [OK]

Hint: Generic rescue clause must come after specific rescue clauses [OK]

Common Mistakes:

• Thinking generic rescue before specific causes syntax error
• Believing ensure block is mandatory
• Assuming rescue clauses only work inside methods

5. Given this Ruby code, what will be printed?

def test
  begin
    raise ArgumentError, 'Wrong argument'
  rescue ZeroDivisionError
    puts 'Zero division error'
  rescue ArgumentError
    puts 'Argument error caught'
  ensure
    puts 'Always runs'
  end
end
test

hard

A. Argument error caught
Always runs

B. Zero division error
Always runs

C. Always runs
Argument error caught

D. No output, error not handled

Solution

1. Step 1: Identify raised error

   The code raises ArgumentError with message 'Wrong argument'.

2. Step 2: Match rescue clauses

   The ArgumentError rescue clause runs and prints 'Argument error caught'.

3. Step 3: Understand ensure block

   The ensure block always runs, printing 'Always runs'.

4. Final Answer:

   Argument error caught Always runs -> Option A

5. Quick Check:

   ArgumentError rescued, ensure always runs [OK]

Hint: Ensure block runs after rescue regardless of error [OK]

Common Mistakes:

• Thinking ensure runs before rescue
• Assuming wrong rescue clause runs
• Ignoring ensure block output