PCAP Practice Test 27 — 15 Questions

Question 1

Drag and drop the steps to debug a Python script using pdb into the correct order.

Accepted Answer

Step 1: Start the pdb debugger. Step 2: Run the script. Step 3: Step through the code. Step 4: Inspect variables. Step 5: Exit the debugger.. Debugging with pdb involves setting a trace, running the script, using commands to step through code, setting breakpoints, and exiting.

Answer

Step 1: Start the pdb debugger. Step 2: Inspect variables. Step 3: Step through the code. Step 4: Run the script. Step 5: Exit the debugger.

Answer

Step 1: Run the script. Step 2: Start the pdb debugger. Step 3: Step through the code. Step 4: Inspect variables. Step 5: Exit the debugger.

Answer

Step 1: Start the pdb debugger. Step 2: Step through the code. Step 3: Run the script. Step 4: Inspect variables. Step 5: Exit the debugger.

Question 2

Refer to the exhibit. What will happen when the code is executed?

Accepted Answer

It raises an AttributeError. The code attempts to call a method or access an attribute that does not exist on the object. In Python, when you try to access an attribute or method that is not defined on an object, an AttributeError is raised. Option C is correct because the exhibit shows an attempt to call a non-existent method or attribute on an instance, which triggers AttributeError.

Answer

It prints None

Answer

It raises a TypeError

Answer

It prints 10

Question 3

You maintain a Python library 'myutils' that is installed as a package in the system. The library has a submodule 'config' that reads configuration from a file. Recently, a user reported that after updating the library, their application still uses the old configuration values. They confirmed that the config file on disk has been updated. The library's __init__.py does: from .config import load_config. The user's application imports load_config from myutils and calls it each time they need configuration. What is the most likely cause of the issue?

Accepted Answer

The library's .pyc files were not regenerated because the .py timestamps were not updated during the install, so Python used the cached bytecode from the previous version.. Python caches compiled bytecode in .pyc files. If the .pyc file's timestamp is newer than the corresponding .py file, Python will use the cached bytecode without recompiling. During a package update, if the .py files' timestamps are not updated (e.g., due to a flawed installation process), Python continues to load the old .pyc, causing the old configuration-reading code to execute even though the config file on disk has changed.

Answer

The user did not restart the Python interpreter, so sys.modules still contains the old module.

Answer

The import statement in __init__.py is cached, so the module is not reloaded even after update.

Answer

The config module caches the configuration file contents in memory after the first read.

Question 4

A developer defines a class with a private attribute `_value` and wants to provide controlled access. Which approach is the most Pythonic?

Accepted Answer

Use @property to define getter and setter methods.. Using the `@property` decorator is the most Pythonic way to implement controlled access to a private attribute. It allows you to define getter and setter methods that can be called like regular attribute access (e.g., `obj.value`), preserving encapsulation while maintaining a clean, non-method-call interface. This approach aligns with Python's philosophy of 'we are all consenting adults' and avoids the verbosity of explicit getter/setter methods.

Answer

Use `__slots__` to restrict attribute creation.

Answer

Make `_value` public and rely on documentation.

Answer

Define `get_value()` and `set_value()` methods.

Question 5

Which THREE of the following are characteristics of Python's special methods (dunder methods)? (Select exactly three.)

Accepted Answer

They enable operator overloading for user-defined classes.. Special methods like `__add__` and `__eq__` allow user-defined classes to redefine the behavior of operators such as `+` and `==`. When Python encounters an operator expression, it looks up the corresponding dunder method on the object's class, enabling operator overloading in a clean, syntactic way.

Answer

Every class automatically has all special methods predefined.

Answer

They must be defined inside the class definition and cannot be added later.

Question 6

Refer to the exhibit. If both data.txt and backup.txt do not exist, what is the output?

Accepted Answer

'No file found'. The code uses a try-except block to catch FileNotFoundError when attempting to open 'data.txt'. In the except block, it prints 'No file found' and then attempts to open 'backup.txt'. Since both files do not exist, the except block executes and prints 'No file found' before the second open attempt raises another FileNotFoundError, which is unhandled and terminates the program. However, the question asks for the output, which is the print statement executed before the error.

Answer

Prints contents of backup.txt

Answer

Nothing

Answer

FileNotFoundError

Question 7

A developer writes a log message with variables: name = 'Alice' and age = 30. Which of the following uses an f-string correctly?

Accepted Answer

f'Name: {name}, Age: {age}'. It uses the proper f-string syntax: the letter 'f' immediately followed by a string literal (single or double quotes) containing expressions in curly braces. In Python, f-strings (formatted string literals) evaluate expressions inside {} and insert them into the string at runtime, making them concise and readable.

Answer

f(Name: {name}, Age: {age})

Answer

'Name: %s, Age: %d' % (name, age)

Answer

f.'Name: {name}, Age: {age}'

Question 8

Which mode should be used when opening a file for writing such that new content is appended to the end without truncating existing content?

Accepted Answer

'a'. ('a') is correct because the 'a' mode opens a file for appending, which means new data is written to the end of the file without truncating any existing content. This is the standard behavior defined in Python's open() function for append mode.

Answer

'x'

Answer

'r+'

Answer

'w'

Question 9

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. 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 10

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'). 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 11

Inside a package 'data', there is a subpackage 'io' and a module 'utils'. Which import statement inside the 'io' subpackage correctly imports the 'helper' function from the sibling module 'utils'?

Accepted Answer

from ..utils import helper. The `..` prefix in a relative import refers to the parent package (`data`), and then `utils` is a sibling module of `io` within that parent package. This allows the `io` subpackage to import the `helper` function from the sibling module `utils` using `from ..utils import helper`.

Answer

import data.utils.helper

Answer

from .utils import helper

Answer

from data.io.utils import helper

Question 12

Which THREE of the following statements about Python's module search path are true?

Accepted Answer

The PYTHONPATH environment variable can be used to add custom directories to sys.path.. Option A is correct because PYTHONPATH is an environment variable whose directories are prepended to the default module search path, effectively extending sys.path so custom modules can be imported. Option C is correct because when a script is executed, Python automatically inserts the directory containing that script at the front of sys.path, allowing sibling modules to be imported. Option E is correct because sys.path is an ordinary Python list that can be modified at runtime (e.g., via sys.path.append() or sys.path.insert()) to alter where subsequent imports are resolved. Option B is wrong because PYTHONPATH directories are searched before site-packages, not after. Option D is wrong because the current working directory is not always the last entry in sys.path; its presence and position depend on how Python is invoked (for example, it appears first when running interactively or with -c/-m, and is not added at all when running a script).

Answer

The site-packages directory is searched before the PYTHONPATH directories.

Answer

The current working directory is always the last entry in sys.path.

Question 13

Consider the following code snippet: 'class A: pass; class B(A): pass; class C(A): pass; class D(B, C): pass'. What is the Method Resolution Order (MRO) for class D according to the C3 linearization algorithm used by Python?

Accepted Answer

D, B, C, A, object. The C3 linearization algorithm merges the linearizations of D's parents (B and C) with their parent list, respecting the local precedence order and monotonicity. For class D(B, C), the MRO is computed as D + merge(L(B), L(C), [B, C]), where L(B) = B, A, object and L(C) = C, A, object. The merge yields D, B, C, A, object, which is the correct MRO.

Answer

D, B, A, C, object

Answer

D, B, C, A

Answer

D, B, A, object, C

Question 14

Refer to the exhibit. What is the output of the code?

Accepted Answer

Programming. The code likely uses slicing with a start index to extract 'Programming' from the string 'Python Programming'. For instance, 'Python Programming'[7:] returns the substring starting at index 7 (after 'Python ' which is 7 characters including space) to the end, which is 'Programming'. This operation is a common way to obtain a substring.

Answer

Program

Answer

Python Programming

Answer

Python

Question 15

A developer is validating user input in a Python application. The string variable `input_str` is assigned the value `'Hello World'`. Which TWO of the following conditions evaluate to `True`? (Choose two.)

Accepted Answer

input_str.istitle(). `istitle()` returns `True` when the string is titlecased, meaning the first character of each word is uppercase and all other characters are lowercase. 'Hello World' has both words starting with an uppercase letter followed by lowercase letters, so it satisfies this condition.

Answer

input_str.isalpha()

Answer

input_str.isalnum()

Answer

input_str.isspace()