PCEP Practice Test 17 — 15 Questions

Question 1

A critical automation system uses a try-except block to handle errors during file operations. The current code uses a bare except: clause to catch any error and perform cleanup. However, when an operator tries to stop the program with Ctrl+C, the KeyboardInterrupt exception is caught, and the cleanup routine runs, preventing a clean exit. Additionally, if the system runs out of memory, MemoryError is caught. The developers need to modify the exception handling so that system-exiting exceptions (such as KeyboardInterrupt and SystemExit) are not caught, but other exceptions (e.g., FileNotFoundError, PermissionError) are still handled for cleanup. Which modification best achieves this?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

Change the bare except: to except Exception:. Changing the bare `except:` to `except Exception:` ensures that only exceptions inheriting from the built-in `Exception` class are caught. System-exiting exceptions like `KeyboardInterrupt` and `SystemExit` inherit from `BaseException` directly, not from `Exception`, so they will propagate uncaught, allowing a clean exit. This preserves the cleanup behavior for file-related errors such as `FileNotFoundError` and `PermissionError`, which are subclasses of `Exception`.

Answer

Remove the except block entirely and rely on a finally block for cleanup

Answer

Replace the single except block with multiple specific except blocks for each expected file error

Answer

Define a custom exception class and raise it for all file errors

Question 2

A program needs to check if a number is both positive and even. Which expression correctly implements this?

Accepted Answer

if num > 0 and num % 2 == 0:. It uses the logical `and` operator to combine two conditions: `num > 0` (checks if the number is positive) and `num % 2 == 0` (checks if the number is even). Both conditions must be true for the overall expression to be true, which correctly implements the requirement of checking if a number is both positive and even.

Answer

if num > 0 or num % 2 == 0:

Answer

if num > 0 & num % 2 == 0:

Answer

if num > 0 and % 2 == 0:

Question 3

A QA engineer needs to run a test 5 times. Which loop construct is most appropriate?

Accepted Answer

for i in range(5): .... The `for i in range(5)` loop is the most idiomatic and concise way to repeat an action a fixed number of times (5 iterations) in Python. The `range(5)` generates a sequence from 0 to 4, and the loop body executes exactly 5 times, which directly matches the requirement to run a test 5 times without needing manual counter management.

Answer

do: ... while counter < 5

Answer

while counter < 5: ... counter += 1

Answer

def repeat(): ... repeat()

Question 4

You are a junior developer at a logistics company. Your team maintains a Python script that processes daily shipment data from a CSV file. The script reads the file, computes total weight per shipment, and writes results to a new CSV. Recently, the script started crashing sporadically with a 'ValueError: invalid literal for int() with base 10: 'NULL''. The CSV file sometimes contains the string 'NULL' in the weight column for missing values. The current code reads the weight column as: weight = int(row['weight']). Your team lead wants a robust fix that handles missing data gracefully without crashing, and also logs the line number for any problematic rows for later review. Which of the following approaches best meets these requirements?

Accepted Answer

Wrap the int conversion in a try-except block: try: weight = int(row['weight']); except ValueError: weight = 0; log the line number using a counter variable.. It uses a try-except block to catch the ValueError when int() fails on 'NULL', sets weight to 0 as a fallback, and logs the line number using a counter variable. This approach handles any unexpected non-numeric string (not just 'NULL'), making it robust against future data anomalies, and satisfies the requirement to log problematic rows for review.

Answer

Use the string method .isdigit(): if row['weight'].isdigit(): weight = int(row['weight']); else: weight = 0; no logging.

Answer

Read the entire file into a list, then use a list comprehension to convert weights: weights = [int(w) if w != 'NULL' else 0 for w in rows] without logging.

Answer

Add a check: if row['weight'] != 'NULL': weight = int(row['weight']); else: weight = 0; and log a warning. Do not use try-except.

Question 5

What is the correct way to read a floating-point number from user input and store it in a variable?

Accepted Answer

x = float(input()). `float(input())` first reads the user input as a string via `input()`, then converts that string to a floating-point number using the `float()` function. This is the standard and only valid way in Python to obtain a float from console input, as `input()` always returns a string.

Answer

x = input(float())

Answer

x = input() as float

Answer

x = input().float()

Question 6

A function sometimes returns None. Which expression correctly checks if the return value is not None?

Accepted Answer

if val is not None:. The `is not` operator is the proper way to check identity inequality in Python. Since `None` is a singleton, comparing with `is not` ensures you are checking whether the value is literally the `None` object, which is the recommended and most readable approach for `None` checks.

Answer

if not val is None:

Answer

if val != None:

Answer

if val:

Question 7

A developer writes the following code: result = (5 + 3) * 2 ** 3 // 4. What is the value of result?

Accepted Answer

16. Python follows the operator precedence rules: exponentiation (**) is evaluated before multiplication and division, and multiplication/division are evaluated before addition/subtraction. The expression evaluates as: 2 ** 3 = 8, then (5 + 3) = 8, then 8 * 8 = 64, then 64 // 4 = 16. The integer division (//) yields an integer result of 16.

Answer

8

Answer

13

Answer

64

Question 8

What is the output of the following code?

def div(a, b):
    try:
        return a / b
    except ZeroDivisionError:
        raise ValueError('Invalid division')

try:
    print(div(10, 0))
except ValueError as e:
    print(e)
except ZeroDivisionError:
    print('Zero division')

Accepted Answer

Invalid division. The `div` function catches the `ZeroDivisionError` and raises a `ValueError` with the message 'Invalid division'. The outer `try` block catches this `ValueError` and prints its message, which is 'Invalid division'.

Answer

Error: division by zero

Answer

Zero division

Answer

TypeError

Question 9

Which TWO of the following list operations modify the list in place?

Accepted Answer

mylist.sort(). `mylist.sort()` sorts the list in place, meaning it modifies the original list object without creating a new one. Option E is correct because `mylist.append(5)` adds the element 5 to the end of the list, directly mutating the original list object.

Answer

mylist + [5]

Answer

mylist.copy()

Answer

mylist = mylist + [5]

Question 10

Which expression evaluates to False?

Accepted Answer

3 > 4. The expression `3 > 4` evaluates to `False` in Python, as 3 is not greater than 4. All other options evaluate to `True` due to the correct application of comparison operators: `<=`, `==`, and `!=`.

Answer

3 <= 3

Answer

3 == 3

Answer

3 != 2

Question 11

A developer is writing a function that takes a list of numbers and returns the sum of all even numbers. Which two code snippets correctly implement this function? (Select two.)

Accepted Answer

def sum_even(nums): total=0; for n in nums: if n%2==0: total+=n; return total. It initializes a total variable to 0, iterates over each number in the list, checks if it is even using the modulo operator (n % 2 == 0), and adds the number to the total. This correctly accumulates the sum of all even numbers and returns the final total.

Answer

def sum_even(nums): return [n for n in nums if n%2==0]

Answer

def sum_even(nums): total=0; for i in range(len(nums)): if nums[i]%2==0: total+=nums[i]*2; return total

Answer

def sum_even(nums): total=0; for n in nums: if n%2==1: total+=n; return total

Question 12

A programmer wants to create a function that can accept any number of keyword arguments and store them in a dictionary. Which function definition is correct?

Accepted Answer

def func(**kwargs):. The **kwargs parameter in a function definition collects any number of extra keyword arguments into a dictionary. The double asterisk (**) is the Python syntax for capturing keyword arguments, and 'kwargs' is the conventional name for the resulting dictionary.

Answer

def func(kwargs):

Answer

def func(**args):

Answer

def func(*kwargs):

Question 13

Given the following code, which of the following statements are true after execution? (Choose three.)

x = 10
y = 3.0
z = x / y
w = x // y

Accepted Answer

The expression x % y is valid.. Option A is correct because x % y uses the modulo operator on an int and a float, which is valid in Python and yields the float remainder 1.0. Option B is correct because x / y performs true division (10 / 3.0), producing the float value approximately 3.3333333333333335. Option E is correct because x // y performs floor division; with a float operand the result is a float, so 10 // 3.0 equals 3.0. Option C is not correct because w is a float (3.0), not an int, since one operand is a float. Option D is not correct because the / operator always returns a float in Python 3, not an integer.

Answer

The type of w is int.

Answer

The expression x / y returns an integer.

Question 14

What is the output of the code?

numbers = [1, 2, 3, 4]
result = [x**2 for x in numbers if x % 2 == 0]
print(result)

Accepted Answer

[4, 16]. The list comprehension `[x**2 for x in numbers if x % 2 == 0]` iterates over `numbers`, filters for even numbers (2 and 4) using the condition `x % 2 == 0`, and squares each selected element. Squaring 2 gives 4, squaring 4 gives 16, so the result is `[4, 16]`. Option B is correct.

Answer

[2, 4]

Answer

[1, 9]

Answer

[2, 4, 16]

Question 15

A developer writes: num = input('Enter a number: '); result = num * 2; print(result). If the user enters 5, what is the output?

Accepted Answer

55. The `input()` function always returns a string. When the user enters '5', `num` is the string '5', not the integer 5. The `*` operator on a string performs repetition, so `'5' * 2` produces '55', which is printed as 55.

Answer

Error: cannot multiply string by int

Answer

10

Answer

'5' * 2