Multiple exception handling in Python - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is multiple exception handling in Python?

It is a way to catch and handle more than one type of error in a single try block using multiple except clauses.

beginner

How do you write multiple except blocks in Python?

You write several except blocks after a try block, each specifying a different exception type to handle.

beginner

What happens if an exception is not caught by any except block?

The program stops and shows an error message called a traceback.

intermediate

Can you catch multiple exceptions in one except block? How?

Yes, by grouping exceptions in a tuple after except, like except (TypeError, ValueError):

intermediate

Why is it useful to handle multiple exceptions separately?

Because different errors may need different fixes or messages, so handling them separately helps make the program clearer and safer.

Which keyword starts the block where you try code that might cause errors?

A try

B except

C catch

D finally

The try block contains code that might raise exceptions.

How do you catch both ValueError and TypeError in one except block?

A except (ValueError, TypeError):

B except ValueError, TypeError:

C except ValueError | TypeError:

D except ValueError & TypeError:

Use a tuple of exceptions inside parentheses after except.

What happens if an exception is raised but no except block matches it?

A The program ignores the error

B The program continues normally

C The program crashes and shows a traceback

D The program restarts automatically

Uncaught exceptions cause the program to stop and print an error traceback.

Which of these is a correct way to handle multiple exceptions separately?

A try: ... except ValueError, TypeError: ...

B try: ... except ValueError & TypeError: ...

C try: ... except ValueError | TypeError: ...

D try: ... except ValueError: ... except TypeError: ...

You write separate except blocks for each exception type.

Why might you want to handle exceptions separately instead of together?

A To make the code longer

B To give specific responses to different errors

C To confuse the reader

D To avoid using try blocks

Different errors may need different fixes or messages.

Explain how to use multiple except blocks to handle different exceptions in Python.

Think about writing one except block for each error you want to catch.

Describe how to catch multiple exceptions in a single except block and why you might do this.

Use parentheses and commas to group exceptions.

Practice

1.

What is the purpose of using multiple except blocks after a single try block in Python?

easy

A. To create multiple loops inside the try block

B. To run the same code multiple times

C. To handle different types of errors separately

D. To ignore all errors silently

Solution

1. Step 1: Understand the role of try-except

   The try block runs code that might cause errors, and except blocks catch those errors.

2. Step 2: Purpose of multiple except blocks

   Multiple except blocks allow catching different error types separately to handle each properly.

3. Final Answer:

   To handle different types of errors separately -> Option C

4. Quick Check:

   Multiple except blocks = handle different errors [OK]

Hint: Multiple except blocks catch different error types separately [OK]

Common Mistakes:

• Thinking multiple except blocks run all at once
• Believing except blocks create loops
• Assuming except blocks ignore errors

2.

Which of the following is the correct syntax to catch both ValueError and TypeError exceptions separately?

try:
    x = int(input())
except ???:
    print("Value error occurred")
except ???:
    print("Type error occurred")

easy

A. except ValueError:
except TypeError:

B. except (ValueError, TypeError):
except Exception:

C. except ValueError, TypeError:
except Exception:

D. except ValueError | TypeError:
except Exception:

Solution

1. Step 1: Check syntax for multiple except blocks

   Each except block must catch one exception type separately using except ExceptionType:.

2. Step 2: Identify correct syntax

   except ValueError: except TypeError: uses separate except blocks for ValueError and TypeError, which is correct syntax.

3. Final Answer:

   except ValueError: except TypeError: -> Option A

4. Quick Check:

   Separate except blocks = except ExceptionType: [OK]

Hint: Use separate except lines for each error type [OK]

Common Mistakes:

• Using commas or pipes inside except incorrectly
• Trying to catch multiple exceptions in one except without tuple
• Using wrong syntax like except ValueError, TypeError:

3.

What will be the output of the following code?

try:
    a = 5 / 0
except ValueError:
    print("Value Error")
except ZeroDivisionError:
    print("Zero Division Error")
else:
    print("No Error")
finally:
    print("Done")

medium

A. Zero Division Error
Done

B. Value Error
Done

C. No Error
Done

D. Zero Division Error

Solution

1. Step 1: Identify the error raised in try block

   The expression 5 / 0 raises a ZeroDivisionError.

2. Step 2: Match the except block and output

   The ZeroDivisionError except block runs, printing "Zero Division Error". The finally block always runs, printing "Done".

3. Final Answer:

   Zero Division Error Done -> Option A

4. Quick Check:

   ZeroDivisionError caught + finally runs = output A [OK]

Hint: Match error type to except block, finally always runs [OK]

Common Mistakes:

• Confusing ValueError with ZeroDivisionError
• Forgetting finally block always runs
• Expecting else block to run on error

4.

Find the error in this code snippet and choose the correct fix:

try:
    x = int('abc')
except ValueError, TypeError:
    print("Error occurred")

medium

A. Change except line to: except ValueError | TypeError:

B. Change except line to: except (ValueError, TypeError):

C. Change except line to: except ValueError, TypeError:

D. No change needed, code is correct

Solution

1. Step 1: Identify syntax error in except line

   The syntax except ValueError, TypeError: is invalid for catching multiple exceptions.

2. Step 2: Correct syntax for multiple exceptions

   Use a tuple of exceptions inside parentheses: except (ValueError, TypeError):.

3. Final Answer:

   Change except line to: except (ValueError, TypeError): -> Option B

4. Quick Check:

   Multiple exceptions need parentheses tuple [OK]

Hint: Use parentheses tuple for multiple exceptions in one except [OK]

Common Mistakes:

• Using commas without parentheses
• Using pipe | operator incorrectly
• Assuming original syntax is valid

5.

You want to write a function that tries to convert a string to an integer and then divide 100 by that number. It should handle ValueError if conversion fails, ZeroDivisionError if division by zero happens, and print "Success" if no error occurs, and print "Done" regardless of errors. Which code correctly implements this?

hard

A. def func(s):
try:
n = int(s)
result = 100 / n
except ValueError:
print("Conversion error")
except ZeroDivisionError:
print("Division by zero")
else:
print("Success")

B. def func(s):
try:
n = int(s)
result = 100 / n
except (ValueError, ZeroDivisionError):
print("Error")
finally:
print("Success")

C. def func(s):
try:
n = int(s)
result = 100 / n
except ValueError:
print("Conversion error")
except ZeroDivisionError:
print("Division by zero")
finally:
print("Success")

D. def func(s):
try:
n = int(s)
result = 100 / n
except ValueError:
print("Conversion error")
except ZeroDivisionError:
print("Division by zero")
else:
print("Success")
finally:
print("Done")

Solution

1. Step 1: Check handling of exceptions and success message

   Function must catch ValueError and ZeroDivisionError separately and print appropriate messages.

2. Step 2: Check use of else and finally blocks

   else runs only if no exception, so "Success" should be printed there. finally always runs, so "Done" can be printed there.

3. Step 3: Verify option correctness

   def func(s): try: n = int(s) result = 100 / n except ValueError: print("Conversion error") except ZeroDivisionError: print("Division by zero") else: print("Success") finally: print("Done") correctly uses separate except blocks, prints "Success" in else, and "Done" in finally.

4. Final Answer:

   Option D code correctly implements all requirements -> Option D

5. Quick Check:

   Separate except + else for success + finally for done [OK]

Hint: Use else for success, finally for cleanup, separate except blocks [OK]

Common Mistakes:

• Printing success in finally instead of else
• Combining exceptions in one except without separate messages
• Omitting finally block when needed