PCAP Practice Test 29 — 15 Questions

Question 1

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

Accepted Answer

It always executes, regardless of exceptions.. The `finally` block in Python is designed to always execute after the `try` and `except` blocks, regardless of whether an exception was raised or not. This includes cases where a `return`, `break`, or `continue` statement is executed in the `try` block, or even if an unhandled exception occurs. The `finally` block is guaranteed to run before the function returns or the exception propagates, ensuring cleanup actions like closing files or releasing resources.

Answer

It executes only if no exception is raised.

Answer

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

Answer

It executes only if an exception is raised.

Question 2

A developer needs to add a custom directory '/home/user/mylibs' to Python's module search path so that modules in that directory can be imported. Which code snippet accomplishes this correctly?

Accepted Answer

import sys; sys.path.append('/home/user/mylibs'). Python's module search path is stored in the list `sys.path`, and the standard way to add a custom directory at runtime is to use the `list.append()` method. This inserts the directory at the end of the search path, allowing modules in that directory to be imported after the standard library and site-packages directories.

Answer

import sys; sys.path.push('/home/user/mylibs')

Answer

import sys; sys.path.add('/home/user/mylibs')

Answer

import path; path.add('/home/user/mylibs')

Question 3

What is the output of the following code?

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

Accepted Answer

err fin. 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 4

When a class defines both __getattr__ and __getattribute__, which one is called when accessing an attribute that exists in the instance?

Accepted Answer

__getattribute__ is called, and __getattr__ is not called.. In Python, when both __getattr__ and __getattribute__ are defined in a class, __getattribute__ is always called first for every attribute access. If the attribute exists in the instance (e.g., in the instance dictionary or via a descriptor), __getattribute__ returns it directly, and __getattr__ is never invoked. __getattr__ is only called as a fallback when __getattribute__ raises an AttributeError. Therefore, for an existing attribute, only __getattribute__ runs, making option D correct.

Answer

__getattr__ always overrides __getattribute__.

Answer

Both __getattr__ and __getattribute__ are called, in that order.

Answer

Only __getattr__ is called.

Question 5

A class MyClass defines __str__ and __repr__ methods. What is the purpose of __repr__?

Accepted Answer

To return an unambiguous representation of the object, ideally for debugging. The `__repr__` method is designed to return an unambiguous string representation of an object, ideally one that can be used to recreate the object or that clearly shows its internal state for debugging purposes. This is distinct from `__str__`, which targets end-user readability. The Python documentation explicitly states that `__repr__` should be unambiguous, while `__str__` should be readable.

Answer

To return a human-readable string for end users

Answer

To compare object equality

Answer

To return a hash value of the object

Question 6

A developer wants to distribute a package that contains both Python code and data files (e.g., images, configs). Which file is used to specify dependencies and metadata for the package?

Accepted Answer

setup.py. setup.py is the standard file used to specify metadata and dependencies for a Python package. It contains information such as the package name, version, author, and a list of required packages (install_requires). It is used by setuptools to build and distribute the package.

Answer

MANIFEST.in

Answer

__init__.py

Answer

requirements.txt

Question 7

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: .... 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 8

Refer to the exhibit. If /var/data/in.csv does not exist, what exception is raised?

Accepted Answer

FileNotFoundError. When a file does not exist and you attempt to open it for reading using the built-in `open()` function, Python raises a `FileNotFoundError`. This is a subclass of `OSError` and is the standard exception for missing files in Python 3. The question explicitly states that `/var/data/in.csv` does not exist, so the correct exception is `FileNotFoundError`.

Answer

configparser.NoSectionError

Answer

PermissionError

Answer

IndexError

Question 9

A team is developing a banking system in Python. They have a base class Account with attributes account_number and balance, and a method __init__(self, account_number, balance) that initializes these attributes. They then create a subclass SavingsAccount that adds an attribute interest_rate. In SavingsAccount's __init__, they assign self.interest_rate = rate but do not call super().__init__. When they instantiate SavingsAccount('12345', 1000, 0.02) and attempt to print(balance), an AttributeError occurs: 'SavingsAccount' object has no attribute 'balance'. What is the most appropriate fix to ensure that the SavingsAccount includes balance and account_number without code duplication?

Accepted Answer

Call super().__init__(account_number, balance) as the first line in SavingsAccount.__init__, then assign self.interest_rate = rate.. In Python, the subclass SavingsAccount overrides __init__ but never invokes the parent's initializer, so account_number and balance are never set on the instance. Calling super().__init__(account_number, balance) as the first line of SavingsAccount.__init__ runs Account's initializer, which assigns those attributes, and then the subclass can safely set self.interest_rate = rate. This is the canonical cooperative-initialization pattern and avoids duplicating the parent's assignment logic.

Answer

Remove the __init__ method from SavingsAccount entirely and rely on the default __init__ from Account.

Answer

Manually assign self.account_number and self.balance in SavingsAccount.__init__ before assigning interest_rate.

Answer

Define balance as a class attribute in Account with a default value and remove it from __init__.

Question 10

A data entry application reads a CSV file where each line contains fields separated by commas. However, some fields are enclosed in double quotes and contain commas inside, e.g., 'John,"Doe, Jr.",30'. The developer currently uses line.split(',') to parse each line, which incorrectly splits the quoted field. The developer wants a solution using only the Python standard library (no third-party packages). Which of the following is the best approach?

Accepted Answer

Use the csv module's reader: import csv; next(csv.reader([line])). The csv module's reader is specifically designed to handle CSV parsing according to RFC 4180, including quoted fields with embedded commas. By passing the line wrapped in a list to csv.reader, the developer gets a properly parsed list of fields without needing to manually handle quote escaping or comma splitting.

Answer

Use line.strip().split(',') and then manually merge fields that start with a quote

Answer

Iterate through each character, track whether inside quotes, and split on commas outside quotes

Answer

Write a regular expression that matches commas outside quotes

Question 11

A junior developer is writing a script that processes user input. The script reads a line of text from the console and needs to remove any leading or trailing whitespace. The developer uses the strip() method but notices that it also removes other characters like newline. However, the requirement is to remove only spaces (not tabs or newlines). Which course of action should the developer take to remove only leading and trailing spaces?

Accepted Answer

Use strip(' ') with a space argument. The strip() method in Python, when called with no arguments, removes all leading and trailing whitespace characters, including spaces, tabs, and newlines. By passing a space character as the argument, strip(' '), the method is instructed to remove only that specific character (space) from the ends of the string, leaving tabs and newlines intact. This directly meets the requirement to remove only leading and trailing spaces.

Answer

Use replace(' ', '') on the string

Answer

Use lstrip() and rstrip() with no arguments

Answer

Use split() and join()

Question 12

Which method returns the lowest index where a specified substring is found, or -1 if not found?

Accepted Answer

find(). The `find()` method in Python returns the lowest index where the specified substring is found within the string, or -1 if the substring is not present. This behavior directly matches the question's requirement, making option A correct.

Answer

locate()

Answer

search()

Answer

index()

Question 13

Which THREE methods return a boolean value?

Accepted Answer

str.startswith(). B is correct because str.startswith() returns True if the string starts with the specified prefix, otherwise False. It is a boolean-returning method, as required by the question.

Answer

str.upper()

Answer

str.find()

Question 14

What is the result of 'PyThon'.lower()?

Accepted Answer

'python'. The `.lower()` method in Python returns a new string with all alphabetic characters converted to lowercase. Since the original string 'PyThon' contains uppercase 'P' and 'T', applying `.lower()` yields 'python'. Option B is correct because it is the only option that shows all characters in lowercase.

Answer

'Python'

Answer

'PYTHON'

Answer

'pYTHON'

Question 15

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. 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