PCAP Exceptions and File I/O Practice Test 3 — 15 Questions

Question 1

Refer to the exhibit. A developer ran the script and saw the above traceback. The intended behavior was to load a JSON configuration file, and if the file is missing, create a default config. What is the most likely root cause of the second exception (NameError)?

Accepted Answer

The script did not import the json module.. Option B is correct because the traceback shows a NameError for 'json.loads', which indicates that the name 'json' is not defined in the current namespace. This occurs when the script attempts to call json.loads() without first importing the json module. The intended behavior of loading a JSON configuration file requires the json module to parse the file content, and its absence causes the NameError exception.

Answer

The variable 'f' was not defined due to the FileNotFoundError.

Answer

The config.json file exists but is empty.

Answer

The file was opened in binary mode instead of text mode.

Question 2

Refer to the exhibit. A developer is writing a script to read this JSON configuration file. The script should write the logging configuration to a separate file called 'logging.conf'. Which file mode should be used to create the file if it doesn't exist, and overwrite it if it does?

Accepted Answer

'w'. Option D ('w') is correct because the 'w' mode opens a file for writing, truncating it first if it exists, and creating it if it does not. This matches the requirement to overwrite an existing 'logging.conf' file or create a new one if absent.

Answer

'x'

Answer

'r+'

Answer

'a'

Question 3

Refer to the exhibit. The above log shows an unhandled exception that caused the program to crash. The developer wants to handle this exception and log the error without crashing. Which exception type should be caught in the main code to capture this specific error?

Accepted Answer

ValueError. The traceback shows that a ValueError was raised. To handle this specific exception, the code should catch ValueError. Catching Exception would also work but is less specific. Catching BaseException catches system-exit exceptions. OSError is unrelated.

Answer

BaseException

Answer

OSError

Answer

Exception

Question 4

A developer writes a script that reads a configuration file. If the file does not exist, the program should print an error and continue. Which code snippet correctly implements this behavior?

Accepted Answer

try: open('config.txt') except FileNotFoundError: print('File not found'). Option A is correct because it uses a `try` block to attempt opening the file and catches only `FileNotFoundError`, which is the specific exception raised when the file does not exist. This allows the program to print an error and continue execution without crashing, precisely matching the requirement.

Answer

f = open('config.txt', 'r') if not f: print('File not found')

Answer

try: f = open('config.txt') except: print('File not found')

Answer

try: with open('config.txt') as f: pass except Exception: print('File not found')

Question 5

Which of the following is the correct way to open a file for writing in binary mode?

Accepted Answer

open('data.dat', 'wb'). Option A is correct because the mode string 'wb' specifies both write ('w') and binary ('b') mode, which is the proper way to open a file for writing binary data in Python. The order of characters in the mode string is fixed: the file mode character ('r', 'w', 'a', etc.) must come first, followed by the optional 'b' for binary mode.

Answer

open('data.dat', 'bw')

Answer

open('data.dat', 'br')

Answer

open('data.dat', 'w')

Question 6

Which method of a file object reads the entire content of a text file as a single string?

Accepted Answer

read(). The `read()` method, when called without arguments or with a negative size, reads the entire contents of a file as a single string. This is the standard Python file object method for reading all text at once, returning a str object. It is the correct choice because the question explicitly asks for a method that returns the entire content as a single string.

Answer

readall()

Answer

readline()

Answer

readlines()

Question 7

What is the output of the following code?

try:
    print(1/0)
except:
    print('err')
finally:
    print('fin')

Accepted Answer

err fin. Option C is correct because when a division by zero occurs, Python raises a ZeroDivisionError, which is caught by the bare except clause, printing 'err'. The finally clause always executes after the except block, printing 'fin'. Thus the output is 'err' followed by 'fin'.

Answer

fin err

Answer

fin

Answer

err

Question 8

A developer wants to ensure that a file is always closed after writing, even if an exception occurs. Which approach is considered best practice in Python?

Accepted Answer

Use the with statement: with open('file.txt', 'w') as f: .... Option D is correct because the `with` statement in Python implements a context manager that automatically calls the file's `__exit__` method, which closes the file even if an exception occurs inside the block. This is the idiomatic and recommended approach for resource management, as it guarantees cleanup without requiring explicit `close()` calls.

Answer

Use try/finally with explicit f.close()

Answer

Rely on the garbage collector to close the file

Answer

Use try/except/finally with f.close() in both except and finally

Question 9

A file is opened with open('test.txt', 'r'). The file object's tell() method returns 0. After reading 10 characters, what does tell() return?

Accepted Answer

10. Option D is correct because the `tell()` method returns the current position of the file pointer in bytes from the beginning of the file. After reading 10 characters (each being 1 byte in a typical text file), the pointer advances by 10 bytes, so `tell()` returns 10.

Answer

File size

Answer

0

Answer

-1

Question 10

What is the output of the following code?

try:
    raise ValueError('a')
except ValueError as e:
    print(e.args[0])
finally:
    print('b')

Accepted Answer

a
b. Option C is correct because the `finally` block always executes after the `try` block, even when an exception is raised. The `except` block catches the `ValueError` and prints the first argument of the exception (`'a'`), then the `finally` block prints `'b'`. The output is `a` on one line and `b` on the next, matching `a
b`.

Answer

a b

Answer

b a

Answer

b

Question 11

Which of the following correctly raises a new exception while preserving the original traceback?

Accepted Answer

raise ValueError('new') from original_exception. Option C is correct because the `raise ... from original_exception` syntax in Python allows you to raise a new exception while chaining it to the original exception, preserving the original traceback. This is essential for debugging, as it shows both the new error and the root cause.

Answer

raise original_exception

Answer

raise ValueError('new')

Answer

raise

Question 12

What is the output of the following code?

try:
    exec('1/0')
except:
    print('error')
else:
    print('no error')
finally:
    print('done')

Accepted Answer

error done. Option A is correct because the `exec('1/0')` raises a `ZeroDivisionError`, which is caught by the bare `except:` clause, printing 'error'. The `else` clause is skipped because an exception occurred, but the `finally` clause always executes, printing 'done'. Thus the output is 'error' followed by 'done'.

Answer

done error

Answer

error

Answer

done

Question 13

Which TWO of the following file modes will create a new file if it doesn't exist? (Select exactly 2)

Accepted Answer

'a'. Option B ('a') is correct because the append mode opens a file for writing at the end; if the file does not exist, Python creates it automatically. Option D ('w') is correct because write mode truncates the file if it exists, but also creates a new file if it does not exist.

Answer

'x'

Answer

'rb'

Answer

'r'

Question 14

Which TWO of the following are appropriate techniques for logging exception details in Python? (Select exactly 2)

Accepted Answer

Using traceback.format_exc(). Option B is correct because `traceback.format_exc()` returns the full traceback as a string, which can be logged or printed to capture detailed exception context. Option E is correct because `logging.exception()` automatically includes the traceback of the current exception when called inside an `except` block, making it the idiomatic way to log exceptions in Python.

Answer

Using print(e.args)

Answer

Using sys.exc_info()

Answer

Using raise without argument

Question 15

Which THREE of the following statements about Python's 'with' statement are true? (Select exactly 3)

Accepted Answer

It can be used with any object that implements __enter__ and __exit__ methods.. Option A is correct because the 'with' statement in Python is designed to work with any object that implements the context management protocol, which consists of the __enter__ and __exit__ methods. This allows the 'with' statement to manage resources beyond just files, such as database connections, locks, or network sockets, as long as the object provides these two methods.

Answer

It eliminates the need for try/finally blocks for resource management.

Answer

It can only be used with file objects.

PCAP Exceptions and File I/O Practice Test 3 — 15 Questions

Exhibit

PCAP Exceptions and File I/O Practice Test 3 — 15 Questions

Exhibit