PCEP Computer Programming and Python Fundamentals Practice Test 10 — 15 Questions

Question 1

A developer writes a function that calculates the area of a rectangle and prints the result inside the function. Later, they need to use this area in another calculation. What should they do to make the function reusable and composable?

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

Accepted Answer

Modify the function to return the area instead of printing it.. Returning a value from a function allows the caller to capture and reuse that value in subsequent calculations, making the function composable and reusable. Printing the result inside the function (as in the original code) only outputs it to the console and discards the value, preventing further programmatic use. By modifying the function to return the area, the developer can assign the result to a variable and use it in other expressions.

Answer

Store the area in a global variable and access it later.

Answer

Keep the function as is and call it from inside another function.

Answer

Pass the area to the next calculation using a print function argument.

Question 2

A Python developer is creating a function that processes a list of dictionaries and needs to ensure the original list remains unchanged. They write the following code:

def process(data):
    for item in data:
        item['processed'] = True
    return data

What is the best-practice critique of this function?

Accepted Answer

The function modifies the original list elements, causing side effects.. The function mutates the dictionaries in the original list by adding the key 'processed' to each one. This violates the principle of avoiding side effects in functions, as the caller's data is changed unexpectedly. In Python, dictionaries are mutable objects, so modifying them inside a function affects the original list elements.

Answer

The indentation should be 2 spaces instead of 4 to conform to PEP 8.

Answer

The function should use a list comprehension instead of a loop.

Answer

The function returns a value but does not use it, which is acceptable.

Question 3

A junior developer is writing a script to read a number from input and double it. They write:

num = input("Enter a number: ")
result = num * 2
print(result)

When they test with input 5, the output is '55' instead of 10. What is wrong?

Accepted Answer

The input is treated as a string; they need to convert it to int.. The `input()` function in Python always returns a string, even if the user types a number. When you use the `*` operator on a string, it repeats the string, so `'5' * 2` yields `'55'`. To perform numeric multiplication, you must convert the input to an integer using `int(input(...))`.

Answer

There is a syntax error in the multiplication line.

Answer

The print function is incorrectly formatting the output.

Answer

The variable name 'num' conflicts with a built-in function.

Question 4

Which THREE of the following code snippets will successfully print the string 'Hello, World!'? (Choose three.)

Accepted Answer

print('''Hello, World!'''). Option A is correct because triple-quoted strings ('''...''') are valid Python string literals, and since the content 'Hello, World!' contains no conflicting triple quotes, print('''Hello, World!''') outputs the string successfully. Option C is correct because a double-quoted string literal "Hello, World!" is valid Python syntax, and print("Hello, World!") outputs the exact text. Option E is correct because a single-quoted string literal 'Hello, World!' is valid Python syntax, and print('Hello, World!') outputs the exact text. Option B is incorrect because the inner double quotes around Hello! terminate the string early, causing a SyntaxError. Option D is incorrect because the apostrophe in It's prematurely closes the single-quoted string, also causing a SyntaxError.

Answer

print("He said, "Hello!"")

Answer

print('It's a beautiful day')

Question 5

You are a junior developer at a small startup. Your team has a Python script that automates daily data processing. The script reads a CSV file, processes each row, and writes results to a new file. Recently, the script started crashing with a 'ValueError: invalid literal for int()' error. The error occurs on a line that converts a field to an integer using int() on a string value. The CSV file comes from an external source that sometimes contains non-numeric values like 'N/A' or empty strings. Which course of action is best to handle this robustly without stopping the entire process?

Accepted Answer

Wrap the conversion in a try-except block and handle the exception appropriately for each row.. Wrapping the conversion in a try-except block allows the script to catch the ValueError for each row individually, log or handle the problematic row (e.g., skip it or use a default value), and continue processing the remaining rows without crashing. This is the standard Pythonic approach for handling expected but unpredictable data quality issues in external input, as it separates error handling from the main logic and preserves the robustness of the batch process.

Answer

Add logging before the conversion to print the problematic value.

Answer

Use a regex to replace all non-digit characters before conversion.

Answer

Contact the external source to ensure no missing values are sent.

Question 6

You are maintaining a Python script that calculates team bonuses based on sales data. The script reads a dictionary where keys are employee names and values are total sales (float). It then applies a 10% bonus if sales exceed 5000. The code snippet is:

def calculate_bonus(sales):
    for name, value in sales.items():
        if value > 5000:
            print(f"{name} gets bonus")

However, the manager wants the script to return a list of employees who qualify, not just print them. They also want to avoid side effects. What is the best way to modify this function?

Accepted Answer

Build a list inside the function and return it at the end.. It modifies the function to build a list of qualifying employee names inside the function and returns that list. This avoids side effects (no global variables, no mutation of the input dictionary) and follows the principle of returning results rather than printing them, making the function reusable and testable.

Answer

Create a global list variable at the top of the script and append each qualifying name to it.

Answer

Keep the function as is and have the caller capture the printed names by redirecting stdout.

Answer

Use the dictionary's update method to mark bonus status in the original sales dictionary.

Question 7

You are a developer in a company that runs a Python script daily to generate reports. The script uses the os module to list files in a directory and process each. Recently, after a server migration, the script fails with 'PermissionError: [Errno 13] Permission denied'. The script runs under a service account that has read/write access to most folders, but the migration changed the permissions on certain subdirectories. The error is intermittent, occurring only for some files. You need to fix the script to continue processing other files even if one fails. Which approach should you take?

Accepted Answer

Use a try-except block inside the loop to catch PermissionError for each file and continue.. By placing a try-except block inside the loop that catches PermissionError specifically, the script can skip the problematic file and continue processing the remaining files. This approach handles the intermittent permission errors gracefully without halting the entire script. Option B is wrong because catching all exceptions silently would mask other critical errors (e.g., bugs in the processing logic). Option C is wrong because os.access() checks may not fully reflect actual runtime permissions due to race conditions and platform-specific behavior, and it requires additional calls that could still fail. Option D is wrong because it relies on external action and does not address the need for the script to be resilient to such errors.

Answer

Wrap the entire processing loop in a try-except that catches all exceptions and passes silently.

Answer

Before processing each file, use os.access() to check permissions and skip if not accessible.

Answer

Ask the server administrator to grant full permissions to the service account on all directories.

Question 8

You are a developer on a team that maintains a legacy Python 2 codebase being migrated to Python 3. One function reads a file in text mode and counts word frequencies. In Python 2, the code used the dict.iteritems() method to iterate over the dictionary. After migration, the code raises AttributeError: 'dict' object has no attribute 'iteritems'. You need to update the code to work in Python 3 while minimizing changes. Which action should you take?

Accepted Answer

Replace iteritems() with items().. In Python 3, the `dict.iteritems()` method was removed because `dict.items()` now returns a view object that provides lazy iteration, similar to what `iteritems()` did in Python 2. Replacing `iteritems()` with `items()` is the minimal change that preserves the iteration behavior and works correctly in Python 3.

Answer

Replace iteritems() with viewitems().

Answer

Replace iteritems() with iteritems() from the six compatibility library.

Answer

Convert the dictionary to a list of tuples and iterate over the list.

Question 9

A junior developer is writing a script to process a list of user IDs: ids = [101, 102, 103, 104]. The goal is to create a new list where each ID is increased by 10, without modifying the original list. The developer writes: new_ids = ids.append(10). However, the output shows None. The developer needs to correctly create the new list. Which code should the developer use to achieve this?

Accepted Answer

new_ids = [id + 10 for id in ids]. It uses a list comprehension to create a new list by adding 10 to each element of the original list `ids`, leaving the original list unchanged. The `append()` method modifies the list in place and returns `None`, which is why the developer got `None`.

Answer

for i in range(len(ids)): ids[i] += 10; new_ids = ids

Answer

new_ids = ids + 10

Answer

new_ids = map(lambda x: x+10, ids)

Question 10

A system administrator is automating server configuration using Python. She has a dictionary: config = {'host': 'localhost', 'port': 8080, 'debug': True}. She needs to add a new key 'timeout' with value 30 if it does not already exist, but only if the 'debug' key is False. If 'debug' is True, she should not add 'timeout'. Additionally, she wants to ensure that the ordering of keys in the dictionary remains stable (insertion order). Which code snippet correctly implements this logic?

Accepted Answer

if not config.get('debug'): config.setdefault('timeout', 30). `config.get('debug')` returns `True` (the value of the 'debug' key), and `not True` evaluates to `False`, so the `if` block is not entered — thus 'timeout' is not added. If 'debug' were `False`, `not False` would be `True`, and `config.setdefault('timeout', 30)` would add the key only if it did not already exist, preserving insertion order (Python 3.7+ guarantees dict order).

Answer

if config.get('debug') == False: config.update({'timeout': 30})

Answer

if config['debug']: config['timeout'] = 30 else: pass

Answer

if config.setdefault('debug', False) == False: config['timeout'] = 30

Question 11

A Python program needs to store the integer value 42 in a variable named count. Which line of code correctly assigns this value?

Accepted Answer

count = 42. The assignment operator = stores a value in a variable. In this scenario, count = 42 correctly binds the name count to the integer 42. The other options either compare, reverse the assignment, or use an operator that is not valid as a standalone statement.

Answer

count == 42

Answer

42 = count

Answer

count := 42

Question 12

A developer is writing a Python script that stores the number of active user sessions in a variable. They want the variable to hold the value 42 as an integer. Which of the following statements correctly assigns the integer 42 to a variable named session_count?

Accepted Answer

session_count = 42. The correct assignment uses the equals sign to bind the integer literal to the variable name. Python does not require type declarations, and the absence of quotes ensures the value is an int. The other options either create a string, use invalid syntax, or misuse an operator not intended for simple assignment.

Answer

session_count := 42

Answer

session_count = '42'

Answer

int session_count = 42

Question 13

A developer writes the following code:

x = 5
if x > 3:
    print('A')
else:
    print('B')
print('C')

What is the output?

Accepted Answer

A
C. With x equal to 5, the condition x > 3 is True, so the if block prints 'A' and the else block is skipped. The final print('C') is outside the conditional structure and always executes. The output is therefore 'A' followed by 'C' on separate lines.

Answer

A
B
C

Answer

B
C

Answer

A

Question 14

A programmer writes:

x = 10
y = 4
print(x // y, x % y, x / y)

What is printed?

Accepted Answer

2 2 2.5. The floor division operator // returns the largest integer less than or equal to the quotient, so 10 // 4 is 2. The modulus operator % returns the remainder, so 10 % 4 is 2. True division / returns a float, so 10 / 4 is 2.5. Printing these in order gives '2 2 2.5'.

Answer

2 0.5 2.5

Answer

2 2 2.0

Answer

2.5 2 2

Question 15

A developer is writing a Python script and needs to create valid variable names. Which two of the following are valid variable names? (Choose two.)

Accepted Answer

total_amount. Valid Python identifiers must start with a letter or underscore, followed by letters, digits, or underscores, and cannot be keywords. _value and total_amount satisfy these rules, while my-var contains a hyphen, 2ndPlace starts with a digit, and for is a keyword.

Answer

2ndPlace

Answer

my-var

Answer

for