PCAP Practice Test 2 — 30 Questions

Question 1

What is the likely outcome of running the following code?

```python
with open("C:\Users\path\file.txt", "r") as f:
    print(f.read())
```

Accepted Answer

The program raises a SyntaxError due to invalid escape sequences.. The code likely contains backslash sequences (e.g., `\U`, `\p`, or other non-standard escapes) that are not valid escape sequences in Python. Starting with Python 3.12, such invalid sequences raise a `SyntaxError` at compile time, preventing the program from running. In earlier versions, a `DeprecationWarning` is issued, but the code may run. The error is not about file operations or path resolution; it's a compile-time syntax error. To avoid this, use raw strings (`r"..."`) or double backslashes (`\`).

Answer

The program runs but the file contents are incorrect.

Answer

The program raises a FileNotFoundError because the path is invalid after escape interpretation.

Answer

The file is opened successfully because backslashes are ignored.

Question 2

A package 'mypkg' has the following structure:
mypkg/
  __init__.py
  submod1.py
  submod2.py
The __init__.py file contains: from . import submod1, submod2. A user runs 'import mypkg' and then 'mypkg.submod1.func()'. However, the user got an AttributeError. What is the most likely cause?

Accepted Answer

The submod1 module does not define a function named 'func'.. The AttributeError indicates that the attribute 'func' was not found on the module object 'submod1'. Since the import statement in __init__.py correctly makes submod1 accessible as mypkg.submod1, the only remaining reason for the error is that submod1.py does not define a function named 'func'. The import mechanism itself is working as intended.

Answer

submod1 is actually a package, not a module, so it cannot be called with 'func()'.

Answer

The __init__.py should use absolute imports like 'import mypkg.submod1' to make submod1 accessible.

Answer

The user must also run 'from mypkg import submod1' before accessing submod1.

Question 3

Drag and drop the steps to define and call a function with default arguments in Python into the correct order.

Accepted Answer

Use the def keyword followed by the function name and parentheses
Specify parameters with default values using the assignment operator
Include a colon and indent the function body
Write the function body with statements that use the parameters
Call the function with only required arguments to use default values
Call the function with all arguments to override defaults. To define a function with default arguments in Python, first use the def keyword, then provide the function name and parentheses. Inside the parentheses, specify any parameters, optionally assigning default values using the assignment operator. Follow with a colon and indent the function body. Finally, call the function by its name, passing arguments as needed. The correct order is 1,2,3,4,5,6.

Answer

Call the function with all arguments to override defaults
Use the def keyword followed by the function name and parentheses
Specify parameters with default values using the assignment operator
Include a colon and indent the function body
Write the function body with statements that use the parameters
Call the function with only required arguments to use default values

Answer

Use the def keyword followed by the function name and parentheses
Specify parameters with default values using the assignment operator
Include a colon and indent the function body
Call the function with only required arguments to use default values
Write the function body with statements that use the parameters
Call the function with all arguments to override defaults

Answer

Use the def keyword followed by the function name and parentheses
Include a colon and indent the function body
Specify parameters with default values using the assignment operator
Write the function body with statements that use the parameters
Call the function with only required arguments to use default values
Call the function with all arguments to override defaults

Question 4

You are a network engineer troubleshooting a script that processes router configuration files. The script reads a configuration line from a file: 'interface GigabitEthernet0/1
 ip address 192.168.1.1 255.255.255.0
 no shutdown'. The script needs to extract the interface name and IP address. The current code uses string split operations but fails when the line has extra spaces or tabs. For example, when the line is 'interface   GigabitEthernet0/1', the split returns ['interface', '', '', 'GigabitEthernet0/1'] and the script fails. You need to modify the script to robustly extract the interface name and IP address regardless of whitespace. Which approach should you take?

Accepted Answer

Use line.split() instead of line.split(' ').. `line.split()` without arguments splits on any whitespace (spaces, tabs, newlines) and automatically removes empty strings, making it robust against extra spaces or tabs. In contrast, `line.split(' ')` splits only on single space characters, leaving empty strings when multiple spaces or tabs are present. This behavior is defined by Python's string method documentation and is essential for parsing configuration files where whitespace is inconsistent.

Answer

Manually iterate and concatenate characters until a space is found.

Answer

Use line.split(' ') and then filter out empty strings.

Answer

Use line.startswith('interface') to identify the line, then extract substring.

Question 5

A developer wants to implement a read-only property for a class 'Temperature' that returns the temperature in Celsius but prevents external modification. Which code snippet correctly defines such a property?

Accepted Answer

class Temperature: @property
def celsius(self): return self._celsius. It defines a read-only property using the `@property` decorator with only a getter method. Without a setter, any attempt to assign a value to `celsius` will raise an `AttributeError`, making the property read-only. This is the standard Pythonic way to implement a read-only attribute.

Answer

class Temperature: @property
def celsius(self): return self._celsius
@celsius.setter
def celsius(self, val): self._celsius = val

Answer

class Temperature: def __setattr__(self, name, val): if name == 'celsius': raise AttributeError

Answer

class Temperature: def __init__(self, c): self.celsius = c

Question 6

A developer is writing a function to reverse each word in a sentence while preserving the original order of the words. For example, 'Hello World' should become 'olleH dlroW'. The current implementation is: def reverse_words(s): return ' '.join(word[::-1] for word in s.split()). This works for simple cases. However, the input may contain multiple spaces between words (e.g., 'Hello   World') and tabs. The requirement is to preserve the exact whitespace between words (including tabs and multiple spaces) in the output. Which of the following modifications will achieve this while keeping the approach efficient?

Accepted Answer

Use re.split(r'(\s+)', s) to separate words and whitespace, then reverse the word parts and join back. `re.split(r'(\s+)', s)` splits the string into a list where every other element is a whitespace segment (preserving exact spaces and tabs), and the word segments can be reversed individually. Joining the list back with `''.join(...)` reconstructs the original whitespace exactly, meeting the requirement efficiently without manual iteration.

Answer

Use s.split(' ') and handle empty strings to preserve spaces, but ignore tabs

Answer

Iterate over the string, detect word boundaries, and build a new string manually

Answer

Use s.split() and then join with the original spaces using a separate loop that tracks whitespace

Question 7

A developer needs to write binary data to a file. Which file mode should be used to open the file for writing in binary mode without truncating it if it already exists?

Accepted Answer

'ab'. ('ab') is correct because the 'a' mode opens the file for appending, which writes data at the end without truncating the existing content, and adding 'b' specifies binary mode. This allows binary data to be written to a file that already exists without losing its current contents.

Answer

'wb'

Answer

'rb'

Answer

'wb+'

Question 8

A developer wants to check if a string 'example.txt' ends with '.txt'. Which expression returns True?

Accepted Answer

'example.txt'.endswith('.txt'). The `endswith()` method is specifically designed to check if a string ends with a given suffix. In this case, `'example.txt'.endswith('.txt')` returns `True` because the string ends with the substring '.txt'.

Answer

'example.txt'.startswith('.txt')

Answer

'example.txt'.find('.txt')

Answer

'example.txt'.rsplit('.',1)

Question 9

Which of the following exception classes is NOT a direct subclass of Exception in Python?

Accepted Answer

SystemExit. SystemExit is not a direct subclass of Exception; it inherits from BaseException instead. This is because SystemExit, along with KeyboardInterrupt and GeneratorExit, is intended to signal that the interpreter should exit, and catching it with a generic except Exception clause would be inappropriate. All other options (IOError, StopIteration, ValueError) are direct subclasses of Exception.

Answer

IOError

Answer

StopIteration

Answer

ValueError

Question 10

Which of the following expressions returns the string 'Hello' repeated three times?

Accepted Answer

'Hello' * 3. In Python, the multiplication operator (*) when used with a string and an integer performs string repetition. 'Hello' * 3 returns the string 'HelloHelloHello' by concatenating three copies of the original string. This is a core feature of Python's sequence protocol, where strings are sequences of characters.

Answer

'Hello' + 3

Answer

'Hello' * '3'

Answer

'Hello' * 3.0

Question 11

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?

Accepted Answer

Division by zero. When the user enters '0', the input is successfully converted to the integer 0 by int(), so no ValueError occurs. Then 10 / 0 raises a ZeroDivisionError, which is caught by the except ZeroDivisionError block, printing 'Division by zero'. Option C is correct because the code never reaches the ValueError handler.

Answer

No output

Answer

Both 'Invalid integer' and 'Division by zero'

Answer

Invalid integer

Question 12

Which expression returns the last character of string s?

Accepted Answer

s[-1]. Python uses zero-based indexing for strings, where negative indices count from the end. s[-1] directly accesses the last character of the string, as -1 refers to the final element in the sequence.

Answer

s[len(s)]

Answer

s[-0]

Answer

s[0]

Question 13

Refer to the exhibit. If the file config.cfg exists but the user does not have read permission, what will be printed?

Accepted Answer

'Permission denied'. When `open()` is called on a file that exists but the user lacks read permission, Python raises a `PermissionError`. Since no exception handling is present, the exception is unhandled and Python prints a traceback to stderr which includes the error message `'Permission denied'` (among other details). Option B correctly identifies the permission-denied message that appears in the output.

Answer

An unhandled exception is raised

Answer

Nothing; the program continues silently

Answer

'File not found'

Question 14

Which TWO statements about Python strings are correct? (Choose exactly 2 correct answers.)

Accepted Answer

Strings are immutable; operations like concatenation produce a new string.. Python strings are immutable, meaning once a string object is created, its content cannot be changed. Any operation that appears to modify a string, such as concatenation with the + operator, actually creates a brand-new string object in memory, leaving the original unchanged.

Answer

Strings are mutable; you can change individual characters via indexing.

Answer

Strings have an .append() method to add characters at the end.

Answer

You can assign a new character to a position in a string using indexing: s[0] = 'a'.

Question 15

A programmer writes a function to check if a string is a palindrome (ignoring case and non-alphanumeric characters). Which implementation correctly achieves this?

Accepted Answer

def is_pal(s): s = ''.join(c for c in s if c.isalnum()).lower(); return s == s[::-1]. It first filters the string to keep only alphanumeric characters using `c.isalnum()`, converts the result to lowercase with `.lower()`, and then compares the string to its reverse using slicing `s[::-1]`. This correctly handles case insensitivity and ignores non-alphanumeric characters, which is the standard approach for palindrome checking in Python.

Answer

def is_pal(s): s = s.lower(); return s == ''.join(reversed(s))

Answer

def is_pal(s): return s == s[::-1]

Answer

def is_pal(s): s = s.lower(); return s == s[::-1]

Question 16

What is the result of the expression 'Hello' * 3?

Accepted Answer

'HelloHelloHello'. In Python, the multiplication operator (*) on a string repeats the string a specified number of times. 'Hello' * 3 concatenates 'Hello' three times, producing 'HelloHelloHello'. This is a fundamental string operation defined in Python's sequence protocol.

Answer

'Hello3'

Answer

'Hello Hello Hello'

Answer

TypeError

Question 17

Which of the following statements about class inheritance in Python are true? (Choose two.)

Accepted Answer

Abstract base classes can be defined using the ABC module.. Python's `abc` module (Abstract Base Classes) allows you to define abstract base classes by inheriting from `ABC` and using the `@abstractmethod` decorator. This enforces that subclasses must implement the abstract methods, providing a formal interface contract.

Answer

A class can inherit from only one base class.

Answer

A child class can override any method from its parent class, but only if the method is declared as virtual.

Answer

The super() function is used to call a method from a sibling class.

Question 18

Which TWO statements are true regarding strings in Python?

Accepted Answer

Strings can be concatenated with the + operator.. Strings in Python support concatenation using the + operator, which joins two or more strings into a single string. This is a fundamental operation for combining textual data, and it works by creating a new string object that contains the characters from both operands in sequence.

Answer

Strings are not sequences.

Answer

Strings are mutable.

Answer

Strings do not support indexing.

Question 19

Which TWO of the following are correct ways to raise a custom exception in Python? (Assume CustomError and CustomException are user-defined.)

Accepted Answer

raise CustomError("invalid"). It raises a user-defined exception by instantiating the custom exception class `CustomError` with an argument (the string "invalid"). In Python, the `raise` statement must be followed by an exception instance or an exception class; `CustomError("invalid")` creates an instance of the custom exception, which is the proper way to raise a custom exception with a custom message.

Answer

raise "Custom error"

Answer

raise 42

Answer

raise Exception

Question 20

Which TWO of the following are valid uses for the '__name__' variable in a Python module?

Accepted Answer

To check if the module is being run as the main program.. The '__name__' variable is set to the string '__main__' when the module is executed directly as the main program (e.g., via 'python module.py'). This allows a module to include code that runs only when it is the entry point, not when it is imported by another module. The check is typically done with 'if __name__ == "__main__":'.

Answer

To get the file path of the module.

Answer

To control which names are exported when using 'from module import *'.

Answer

To determine which module imported it.