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Exceptions and File I/O practice questions

Practise Certified Associate Python Programmer PCAP Exceptions and File I/O practice questions — original exam-style scenarios with answer choices, explanations, and analysis of common mistakes.

Courseiva uses original exam-style practice questions designed for learning and revision. The goal is to understand the concepts, recognise exam patterns, and improve through explanations — not memorise copied exam dumps.

Reviewed byJohnson Ajibi· MSc IT Security

20 questionsDomain: Exceptions and File I/O

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What the exam tests

What to know about Exceptions and File I/O

Exceptions and File I/O questions test whether you can apply the concept in context, not just recognise a definition.

How the topic appears in realistic exam-style scenarios.

Which detail in the question changes the correct answer.

How to eliminate plausible but wrong options.

How to connect the question back to the wider exam objective.

Watch out for

Common Exceptions and File I/O exam traps

▸Answering from memory before reading the full scenario.
▸Missing a constraint such as cost, availability, security, scope or command context.
▸Choosing a broad answer when the question asks for the most specific fix.
▸Ignoring why the wrong options are tempting.

Practice set

Exceptions and File I/O questions

20 questions · select your answer, then reveal the explanation

Question 1easymultiple choice

Read the full Exceptions and File I/O explanation →

A developer writes a function that reads a configuration file and returns its contents as a string. The file might not exist. Which exception should be caught to handle a missing file?

Trap 1: PermissionError

PermissionError is for access issues, not missing file.

Trap 2: IOError

IOError is an alias for OSError, not specific to missing file.

Trap 3: OSError

OSError is too broad; it includes other I/O errors.

Study all Exceptions and File I/O common traps →

A
FileNotFoundError
FileNotFoundError is specifically for missing files.
B
PermissionError
Why wrong: PermissionError is for access issues, not missing file.
C
IOError
Why wrong: IOError is an alias for OSError, not specific to missing file.
D
OSError
Why wrong: OSError is too broad; it includes other I/O errors.

Full breakdown with real-world context →

Question 2mediummultiple choice

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A Python script processes a log file line by line. If a line cannot be decoded due to an encoding error, the script should skip the line and continue. Which exception handling approach is best?

Trap 1: Wrap the entire file reading in a try-except block without…

Bare except hides all errors, including programming mistakes.

Trap 2: Use a try-except-else block to handle success and failure…

Exiting on failure is not desired.

Trap 3: Catch Exception in the outer loop and break on error.

Catching Exception is broad and causing loop exit.

Study all Exceptions and File I/O common traps →

A
Wrap the entire file reading in a try-except block without specifying exception type.
Why wrong: Bare except hides all errors, including programming mistakes.
B
Use a try-except-else block to handle success and failure separately, exiting on failure.
Why wrong: Exiting on failure is not desired.
C
Inside the loop, wrap the line decoding in a try-except UnicodeDecodeError block and continue.
This isolates decoding issues and continues processing.
D
Catch Exception in the outer loop and break on error.
Why wrong: Catching Exception is broad and causing loop exit.

Full breakdown with real-world context →

Question 3hardmultiple choice

Read the full Exceptions and File I/O explanation →

A developer implements a custom exception class `DataError` that inherits from `Exception`. Which method override is essential to ensure the exception message is properly displayed when caught?

Trap 1: Set the __cause__ attribute in __init__.

__cause__ is for exception chaining, not message display.

Trap 2: Override __str__ to return a formatted string.

Exception already provides __str__ if message is passed to init.

Trap 3: Override __repr__ to return a detailed representation.

__repr__ is not used for displaying exception messages.

Study all Exceptions and File I/O common traps →

A
Override __init__ to accept a message and call super().__init__(message).
This ensures the message is stored and displayed.
B
Set the __cause__ attribute in __init__.
Why wrong: __cause__ is for exception chaining, not message display.
C
Override __str__ to return a formatted string.
Why wrong: Exception already provides __str__ if message is passed to init.
D
Override __repr__ to return a detailed representation.
Why wrong: __repr__ is not used for displaying exception messages.

Full breakdown with real-world context →

Question 4easymultiple choice

Read the full Exceptions and File I/O explanation →

Which of the following is the correct way to open a file for writing in text mode, ensuring that if the file already exists it will be overwritten?

Trap 1: open('file.txt', 'x')

'x' mode raises FileExistsError if file exists.

Trap 2: open('file.txt', 'r+')

'r+' mode does not truncate; it writes from the beginning.

Trap 3: open('file.txt', 'a')

'a' mode appends to the end.

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A
open('file.txt', 'x')
Why wrong: 'x' mode raises FileExistsError if file exists.
B
open('file.txt', 'w')
'w' mode overwrites existing content.
C
open('file.txt', 'r+')
Why wrong: 'r+' mode does not truncate; it writes from the beginning.
D
open('file.txt', 'a')
Why wrong: 'a' mode appends to the end.

Full breakdown with real-world context →

Question 5mediummultiple choice

Read the full Exceptions and File I/O explanation →

A script uses `with open('data.bin', 'rb') as f:` to read binary data. Within the block, which method should be used to read exactly 4 bytes?

Trap 1: f.seek(4)

Moves file pointer, does not read.

Trap 2: f.readline()

Reads a line, not binary.

Trap 3: f.read()

Reads the whole file.

Study all Exceptions and File I/O common traps →

A
f.read(4)
Reads up to 4 bytes.
B
f.seek(4)
Why wrong: Moves file pointer, does not read.
C
f.readline()
Why wrong: Reads a line, not binary.
D
f.read()
Why wrong: Reads the whole file.

Full breakdown with real-world context →

Question 6hardmultiple choice

Read the full Exceptions and File I/O explanation →

Consider the following code snippet:

try:

x = int(input()) y = 10 / x

print(y)

except ZeroDivisionError:

print('Division by zero')

except ValueError:

print('Invalid integer')

If the user enters '0', what is the output?

Trap 1: No output

The error is caught and message printed.

Trap 2: Both 'Invalid integer' and 'Division by zero'

Only one exception is raised.

Trap 3: Invalid integer

No ValueError since '0' is a valid integer.

Study all Exceptions and File I/O common traps →

A
No output
Why wrong: The error is caught and message printed.
B
Both 'Invalid integer' and 'Division by zero'
Why wrong: Only one exception is raised.
C
Division by zero
ZeroDivisionError is raised and caught.
D
Invalid integer
Why wrong: No ValueError since '0' is a valid integer.

Full breakdown with real-world context →

Question 7easymultiple choice

Read the full Exceptions and File I/O explanation →

Which of the following statements about the `finally` block is true?

Trap 1: It executes only if no exception is raised.

Finally always executes.

Trap 2: It does not execute if a return statement is in try block.

Finally executes even after return.

Trap 3: It executes only if an exception is raised.

Finally always executes.

Study all Exceptions and File I/O common traps →

A
It executes only if no exception is raised.
Why wrong: Finally always executes.
B
It does not execute if a return statement is in try block.
Why wrong: Finally executes even after return.
C
It executes only if an exception is raised.
Why wrong: Finally always executes.
D
It always executes, regardless of exceptions.
Finally is guaranteed to run.

Full breakdown with real-world context →

Question 8mediummultiple choice

Read the full Exceptions and File I/O explanation →

A programmer wants to catch both `FileNotFoundError` and `PermissionError` with a single except clause. Which tuple is correct?

Trap 1: except FileNotFoundError, PermissionError:

Invalid syntax; use parentheses.

Trap 2: except OSError:

Too broad; catches other OSErrors.

Trap 3: except [FileNotFoundError, PermissionError]:

List is not valid; use tuple.

Study all Exceptions and File I/O common traps →

A
except (FileNotFoundError, PermissionError):
Correct tuple syntax.
B
except FileNotFoundError, PermissionError:
Why wrong: Invalid syntax; use parentheses.
C
except OSError:
Why wrong: Too broad; catches other OSErrors.
D
except [FileNotFoundError, PermissionError]:
Why wrong: List is not valid; use tuple.

Full breakdown with real-world context →

Question 9mediummulti select

Study the full Python automation breakdown →

Which TWO of the following are valid ways to raise an exception in Python?

Trap 1: raise

Valid only inside except block to re-raise.

Trap 2: raise Exception

Missing parentheses; should be Exception().

Trap 3: throw ValueError('error')

'throw' is not Python; use 'raise'.

Study all Exceptions and File I/O common traps →

A
raise
Why wrong: Valid only inside except block to re-raise.
B
raise Exception
Why wrong: Missing parentheses; should be Exception().
C
throw ValueError('error')
Why wrong: 'throw' is not Python; use 'raise'.
D
raise Exception('error')
Correct syntax to raise an exception with message.
E
raise ValueError('invalid value')
Raises a specific exception.

Full breakdown with real-world context →

Question 10hardmulti select

Read the full Exceptions and File I/O explanation →

Which THREE of the following are true about the `with` statement for file handling?

Trap 1: It can only be used with files.

Can be used with any context manager.

Trap 2: It can only handle one file at a time.

Multiple files can be managed with nested or comma-separated with statements.

Study all Exceptions and File I/O common traps →

A
It can only be used with files.
Why wrong: Can be used with any context manager.
B
It can only handle one file at a time.
Why wrong: Multiple files can be managed with nested or comma-separated with statements.
C
It uses the __enter__ and __exit__ methods of the file object.
These methods implement the context manager.
D
It ensures the file is closed even if an exception occurs inside the block.
True, __exit__ is called even on exception.
E
It automatically closes the file when the block exits.
True, the file is closed after the block.

Full breakdown with real-world context →

Question 11easymulti select

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Which TWO of the following are built-in Python exceptions?

Trap 1: CustomException

User-defined, not built-in.

Trap 2: InputError

Not a built-in exception.

Trap 3: FileReadError

Not a built-in exception.

Study all Exceptions and File I/O common traps →

A
CustomException
Why wrong: User-defined, not built-in.
B
InputError
Why wrong: Not a built-in exception.
C
ValueError
Built-in exception for invalid value.
D
FileNotFoundError
Built-in exception for missing files.
E
FileReadError
Why wrong: Not a built-in exception.

Full breakdown with real-world context →

Question 12hardmultiple choice

Study the full Python automation breakdown →

What is the output of the Python code after reading the config.txt file?

Exhibit

Refer to the exhibit.

# config.txt
[Settings]
host = localhost
port = 8080
debug = True

# Python code
import configparser

config = configparser.ConfigParser()
config.read('config.txt')
port = config.getint('Settings', 'port')
print(port)

Trap 1: 8080 (as string)

It returns integer.

Trap 2: An exception is raised.

File is valid and section exists.

Trap 3: '8080'

getint returns integer, not string.

Study all Exceptions and File I/O common traps →

A
8080 (as string)
Why wrong: It returns integer.
B
An exception is raised.
Why wrong: File is valid and section exists.
C
8080
getint returns integer 8080.
D
'8080'
Why wrong: getint returns integer, not string.

Full breakdown with real-world context →

Question 13mediummultiple choice

Read the full Exceptions and File I/O explanation →

What is the output of the code?

Exhibit

Refer to the exhibit.

# error.log
2025-03-15 10:23:45 ERROR: Division by zero in module calc.py line 42
2025-03-15 10:23:46 WARNING: Low disk space on /dev/sda1
2025-03-15 10:23:47 INFO: User login successful

# Python code
try:
    with open('error.log', 'r') as f:
        for line in f:
            if 'ERROR' in line:
                raise RuntimeError(line.strip())
except RuntimeError as e:
    print('Error found:', e)

Trap 1: Prints all lines in the file.

Only prints the error message.

Trap 2: Raises an unhandled exception.

Exception is caught by except.

Trap 3: Prints all lines containing 'ERROR'

Only first ERROR triggers raise.

Study all Exceptions and File I/O common traps →

A
Prints all lines in the file.
Why wrong: Only prints the error message.
B
Raises an unhandled exception.
Why wrong: Exception is caught by except.
C
Prints all lines containing 'ERROR'
Why wrong: Only first ERROR triggers raise.
D
Error found: 2025-03-15 10:23:45 ERROR: Division by zero in module calc.py line 42
First ERROR line is raised and printed.

Full breakdown with real-world context →

Question 14hardmultiple choice

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You are a Python developer at a financial firm. Your team maintains a high-frequency trading system that reads real-time market data from a binary file 'market_feed.bin'. The file is updated every millisecond by an external process. Your script uses a `with` statement to open the file in binary read mode and reads exactly 1024 bytes each iteration in an infinite loop. Recently, the script has been crashing intermittently with an `OSError` with message '[Errno 9] Bad file descriptor'. The error occurs at random times, sometimes after minutes, sometimes after hours. The system runs on Linux. The script runs as a daemon. You suspect the issue is related to file descriptor exhaustion or the external process manipulating the file. What is the most likely cause and the best course of action?

Trap 1: Open the file without using a context manager and manually close it…

Manual close does not prevent the external process from invalidating the descriptor.

Trap 2: Increase the read buffer size to 4096 bytes to reduce the number of…

This does not fix the underlying file descriptor issue.

Trap 3: Catch OSError and re-open the file within the except block, then…

This can work but may still encounter the error if the file is truncated repeatedly; also does not address the root cause.

Study all Exceptions and File I/O common traps →

A
Open the file without using a context manager and manually close it after each read.
Why wrong: Manual close does not prevent the external process from invalidating the descriptor.
B
Increase the read buffer size to 4096 bytes to reduce the number of read operations.
Why wrong: This does not fix the underlying file descriptor issue.
C
Catch OSError and re-open the file within the except block, then continue reading.
Why wrong: This can work but may still encounter the error if the file is truncated repeatedly; also does not address the root cause.
D
Use file locking (e.g., fcntl.flock) to coordinate access with the external process, and re-open the file if a lock cannot be acquired.
File locking prevents the external process from truncating the file while your script is reading, avoiding the bad file descriptor.

Full breakdown with real-world context →

Question 15mediumdrag order

Study the full Python automation breakdown →

Drag and drop the steps to read a CSV file using the csv module in Python into the correct order.

Drag steps to the numbered slots on the right, or tap a step then tap a slot.

Steps

Order

1Step 1

2Step 2

3Step 3

4Step 4

5Step 5

Question 16mediumdrag order

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Drag and drop the steps to serialize a Python object to JSON using the json module into the correct order.

Drag steps to the numbered slots on the right, or tap a step then tap a slot.

Steps

Order

1Step 1

2Step 2

3Step 3

4Step 4

5Step 5

Question 17mediummatching

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Match each Python data structure to its mutability.

Drag a concept onto its matching description — or click a concept then click the description.

Concepts

Matches

Mutable

Immutable

Mutable

Immutable

Mutable

Question 18mediummatching

Study the full Python automation breakdown →

Match each Python module to its purpose.

Drag a concept onto its matching description — or click a concept then click the description.

Concepts

Matches

Mathematical functions

Generate pseudo-random numbers

Manipulate dates and times

Work with JSON data

Interact with operating system

Question 19easymultiple choice

Read the full Exceptions and File I/O explanation →

A developer writes a function that reads a file and processes its content. The function should handle the case where the file does not exist without catching other I/O errors. Which exception should be caught?

Trap 1: PermissionError

PermissionError is raised for permission issues, not for missing files.

Trap 2: IOError

IOError is deprecated in Python 3 and too broad; it catches any I/O error, not just missing files.

Trap 3: OSError

OSError is the parent of FileNotFoundError and includes many other OS errors, making it too broad.

Study all Exceptions and File I/O common traps →

A
PermissionError
Why wrong: PermissionError is raised for permission issues, not for missing files.
B
IOError
Why wrong: IOError is deprecated in Python 3 and too broad; it catches any I/O error, not just missing files.
C
OSError
Why wrong: OSError is the parent of FileNotFoundError and includes many other OS errors, making it too broad.
D
FileNotFoundError
FileNotFoundError is the specific exception for a missing file, ideal for this scenario.

Full breakdown with real-world context →

Question 20mediummultiple choice

Read the full Exceptions and File I/O explanation →

A developer is writing a script that processes user-uploaded CSV files. The script should attempt to read the file, and if a UnicodeDecodeError occurs, log a warning and skip the file. Which code snippet correctly achieves this without stopping the entire process?

Trap 1: try: read_file() except (UnicodeDecodeError, OSError): pass

Passes silently without logging, which is not best practice for debugging.

Trap 2: try: read_file() except Exception: log.warning('Skipping file')

Catches all exceptions, including critical ones like KeyboardInterrupt, which is too broad.

Trap 3: try: read_file() except UnicodeEncodeError: log.warning('Skipping…

UnicodeEncodeError occurs during encoding, not decoding; wrong exception.

Study all Exceptions and File I/O common traps →

A
try: read_file() except (UnicodeDecodeError, OSError): pass
Why wrong: Passes silently without logging, which is not best practice for debugging.
B
try: read_file() except UnicodeDecodeError: log.warning('Skipping file')
Correctly catches only UnicodeDecodeError and continues with next file.
C
try: read_file() except Exception: log.warning('Skipping file')
Why wrong: Catches all exceptions, including critical ones like KeyboardInterrupt, which is too broad.
D
try: read_file() except UnicodeEncodeError: log.warning('Skipping file')
Why wrong: UnicodeEncodeError occurs during encoding, not decoding; wrong exception.

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Frequently asked questions

What does the PCAP exam test about Exceptions and File I/O?: Exceptions and File I/O questions test whether you can apply the concept in context, not just recognise a definition.
How should I use these practice questions?: Select your answer before revealing the explanation. Then read why each option is right or wrong — this active recall approach builds retention far faster than re-reading notes.
Can I practise just Exceptions and File I/O questions in a focused session?: Yes — the session launcher on this page draws every question from the Exceptions and File I/O domain. Use a 10-question session first to gauge your baseline, then move to 20 or 30 once the weak spots are clear.
Where can I practise other PCAP topics?: Use the topic links above to move to related areas, or go back to the PCAP question bank to see all topics.
Are these real exam questions or dumps?: These are original practice questions written to test the same concepts the PCAP exam covers. They are not copied from any real exam or dump site.

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All PCAP questions Exceptions and File I/O domain overview PCAP exam guide

Exam traps to avoid

▸Answering from memory before reading the full scenario.
▸Missing a constraint such as cost, availability, security, scope or command context.
▸Choosing a broad answer when the question asks for the most specific fix.
▸Ignoring why the wrong options are tempting.

Exceptions and File I/O practice questions

What to know about Exceptions and File I/O

Common Exceptions and File I/O exam traps

Exceptions and File I/O questions

A developer writes a function that reads a configuration file and returns its contents as a string. The file might not exist. Which exception should be caught to handle a missing file?

A Python script processes a log file line by line. If a line cannot be decoded due to an encoding error, the script should skip the line and continue. Which exception handling approach is best?

A developer implements a custom exception class `DataError` that inherits from `Exception`. Which method override is essential to ensure the exception message is properly displayed when caught?

Which of the following is the correct way to open a file for writing in text mode, ensuring that if the file already exists it will be overwritten?

A script uses `with open('data.bin', 'rb') as f:` to read binary data. Within the block, which method should be used to read exactly 4 bytes?

Which of the following statements about the `finally` block is true?

A programmer wants to catch both `FileNotFoundError` and `PermissionError` with a single except clause. Which tuple is correct?

Which TWO of the following are valid ways to raise an exception in Python?

Which THREE of the following are true about the `with` statement for file handling?

Which TWO of the following are built-in Python exceptions?

What is the output of the Python code after reading the config.txt file?

Exhibit

What is the output of the code?

Exhibit

Drag and drop the steps to read a CSV file using the csv module in Python into the correct order.

Drag and drop the steps to serialize a Python object to JSON using the json module into the correct order.

Match each Python data structure to its mutability.

Match each Python module to its purpose.

A developer writes a function that reads a file and processes its content. The function should handle the case where the file does not exist without catching other I/O errors. Which exception should be caught?

A developer is writing a script that processes user-uploaded CSV files. The script should attempt to read the file, and if a UnicodeDecodeError occurs, log a warning and skip the file. Which code snippet correctly achieves this without stopping the entire process?

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