Common exception types in Python - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to catch a division by zero error.

Python

try:
    result = 10 / 0
except [1]:
    print("Cannot divide by zero!")

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

AValueError

BZeroDivisionError

CTypeError

DIndexError

Attempts:

3 left

💡 Hint

Common Mistakes

Using ValueError instead of ZeroDivisionError.

Using TypeError which is for wrong data types.

The ZeroDivisionError is raised when you try to divide a number by zero.

2fill in blank

medium

Complete the code to catch an error when accessing a list index that does not exist.

Python

my_list = [1, 2, 3]
try:
    print(my_list[5])
except [1]:
    print("Index out of range!")

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

AKeyError

BValueError

CAttributeError

DIndexError

Attempts:

3 left

💡 Hint

Common Mistakes

Using KeyError which is for dictionary keys.

Using AttributeError which is for missing object attributes.

IndexError occurs when you try to access an index that is not in the list.

3fill in blank

hard

Fix the error in the code by catching the correct exception type when converting a string to an integer.

Python

user_input = "abc"
try:
    number = int(user_input)
except [1]:
    print("Invalid number!")

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

AValueError

BTypeError

CNameError

DZeroDivisionError

Attempts:

3 left

💡 Hint

Common Mistakes

Using TypeError which is for wrong data types, not invalid values.

Using ZeroDivisionError which is unrelated.

ValueError is raised when conversion from string to int fails due to invalid format.

4fill in blank

hard

Fill both blanks to catch errors when opening a file that does not exist and when reading from it.

Python

try:
    with open('missing.txt', '[1]') as file:
        content = file.read()
except [2]:
    print("File error occurred.")

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

Ar

Bw

CFileNotFoundError

DIOError

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'w' mode which creates a file instead of reading.

Catching IOError instead of FileNotFoundError.

Opening a file for reading uses mode 'r'. If the file is missing, FileNotFoundError is raised.

5fill in blank

hard

Fill all three blanks to create a dictionary comprehension that includes only keys with string values longer than 3 characters.

Python

data = {'a': 'cat', 'b': 'elephant', 'c': 42}
result = {k: v for k, v in data.items() if isinstance(v, [1]) and len(v) [2] [3]

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

Astr

B>

C3

Dint

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'int' instead of 'str' for type check.

Using '<' instead of '>' for length comparison.

We check if the value is a string with isinstance(v, str), then check if its length is greater than 3.

Practice

1. Which exception is raised when you try to divide a number by zero in Python?

easy

A. ValueError

B. ZeroDivisionError

C. IndexError

D. TypeError

Solution

1. Step 1: Understand division by zero

   Dividing any number by zero is mathematically undefined and causes an error in Python.

2. Step 2: Identify the exception type

   Python raises a ZeroDivisionError when division by zero occurs.

3. Final Answer:

   ZeroDivisionError -> Option B

4. Quick Check:

   Division by zero = ZeroDivisionError [OK]

Hint: Division by zero always raises ZeroDivisionError [OK]

Common Mistakes:

• Confusing ZeroDivisionError with ValueError
• Thinking IndexError occurs for division
• Assuming TypeError is raised for zero division

2. Which of the following code snippets will raise a ValueError?

easy

A. open('file.txt')

B. 5 / 0

C. my_list[10] where my_list has 5 elements

D. int('abc')

Solution

1. Step 1: Analyze each option for ValueError

   int('abc') tries to convert a non-numeric string to int, which causes ValueError.

2. Step 2: Check other options for different exceptions

   5 / 0 causes ZeroDivisionError, C causes IndexError, A may cause FileNotFoundError.

3. Final Answer:

   int('abc') -> Option D

4. Quick Check:

   Invalid int conversion = ValueError [OK]

Hint: ValueError occurs when conversion or value is invalid [OK]

Common Mistakes:

• Confusing ZeroDivisionError with ValueError
• Assuming file open errors cause ValueError
• Mixing IndexError with ValueError

3. What will be the output of this code?

my_list = [1, 2, 3]
print(my_list[3])

medium

A. IndexError

B. 3

C. None

D. ValueError

Solution

1. Step 1: Understand list indexing

   List indices start at 0, so valid indices for my_list are 0, 1, 2.

2. Step 2: Accessing index 3

   Index 3 is out of range, so Python raises an IndexError.

3. Final Answer:

   IndexError -> Option A

4. Quick Check:

   Out of range index = IndexError [OK]

Hint: Accessing invalid list index raises IndexError [OK]

Common Mistakes:

• Thinking it returns last element
• Assuming None is returned for invalid index
• Confusing IndexError with ValueError

4. Identify the error in this code snippet:

try:
    x = int('hello')
except ZeroDivisionError:
    print('Cannot divide by zero')

medium

A. Wrong exception caught, should catch ValueError

B. SyntaxError due to missing colon

C. No error, code runs fine

D. ZeroDivisionError will be raised

Solution

1. Step 1: Analyze the try block

   int('hello') raises ValueError because 'hello' cannot convert to int.

2. Step 2: Check except block

   Except block catches ZeroDivisionError, which does not handle ValueError, so error is uncaught.

3. Final Answer:

   Wrong exception caught, should catch ValueError -> Option A

4. Quick Check:

   Exception type mismatch = catch correct exception [OK]

Hint: Catch the exact exception your code may raise [OK]

Common Mistakes:

• Catching wrong exception type
• Assuming code runs without error
• Confusing syntax errors with exception handling

5. You want to safely convert user input to an integer and print it. Which code correctly handles invalid input without crashing?

hard

A. try:
num = int(input())
except ZeroDivisionError:
print('Invalid number')

B. num = int(input())
print(num)

C. try:
num = int(input())
except ValueError:
print('Invalid number')

D. num = input()
print(int(num))

Solution

1. Step 1: Understand input conversion risks

   User input may not be a valid integer, causing ValueError on conversion.

2. Step 2: Check exception handling

   try: num = int(input()) except ValueError: print('Invalid number') uses try-except to catch ValueError and print a message, preventing crash.

3. Final Answer:

   try-except catching ValueError with message -> Option C

4. Quick Check:

   Handle invalid input with ValueError catch [OK]

Hint: Use try-except to catch ValueError on int conversion [OK]

Common Mistakes:

• Not catching exceptions causing program crash
• Catching wrong exception type like ZeroDivisionError
• Assuming input is always valid integer