PCEP Timed Practice Test 4 — 10 Questions

Question 1

Which TWO of the following are valid ways to create a list with elements 10, 20, 30?

Accepted Answer

my_list = [x for x in (10,20,30)]. Option A is correct because it uses a list comprehension that iterates over the tuple (10, 20, 30) and creates a new list with the same elements. This is a valid Python syntax for constructing a list from an iterable.

Answer

my_list = list(10, 20, 30)

Answer

my_list = [10; 20; 30]

Question 2

A programmer wants to iterate over a list of strings and print each string in uppercase. Which of the following code snippets will accomplish this?

Accepted Answer

for item in my_list: print(item.upper()). Option D is correct because it correctly calls the `upper()` method on each string `item` in the list `my_list` and prints the result. The `upper()` method returns a new string with all characters converted to uppercase, and the `print()` function outputs that value to the console.

Answer

for item in my_list: print(item.upper)

Answer

for item in my_list: item.upper() print(item)

Answer

for i in my_list: print(my_list[i].upper())

Question 3

A script uses the // operator with negative numbers. For example, -7 // 2 returns -4. The developer expected -3. Which statement best explains this behavior?

Accepted Answer

The // operator performs floor division, which rounds down to the next lower integer.. In Python, the // operator performs floor division, which always rounds down to the next lower integer (toward negative infinity). For -7 // 2, the exact result is -3.5, and floor division rounds down to -4, not -3. This behavior is defined by the Python language specification and differs from truncation toward zero.

Answer

The // operator uses banker's rounding.

Answer

The // operator truncates toward zero for negative numbers.

Answer

The // operator performs integer division with rounding to the nearest even integer.

Question 4

A developer needs to store a large collection of unique user IDs (integers) and quickly check if a new ID already exists. Which data type is most appropriate for this task?

Accepted Answer

set. A set is the most appropriate data type because it stores unordered collections of unique elements and provides O(1) average-time complexity for membership testing using the `in` operator. This makes it ideal for quickly checking if a new user ID already exists without needing to manage keys or maintain order.

Answer

dict

Answer

list

Answer

tuple

Question 5

A list contains strings and numbers: items = ['apple', 10, 'banana', 20]. A programmer wants to create a new list that contains only the strings. Which approach is correct?

Accepted Answer

[item for item in items if type(item) == str]. Option C is correct because `type(item) == str` directly compares the type of each item to the `str` type object, which returns `True` for strings and `False` for numbers. This is a valid and explicit way to filter the list comprehension to only include string elements.

Answer

[item for item in items if item.isdigit()]

Answer

[item for item in items if type(item) is 'str']

Question 6

A programmer needs to swap the values of two variables a and b without using a temporary variable. Which approach works in Python?

Accepted Answer

a, b = b, a. Option B is correct because Python supports tuple unpacking, which allows the values of a and b to be swapped in a single atomic operation: a, b = b, a. This works by creating a tuple (b, a) on the right-hand side, then unpacking it into the variables on the left, effectively swapping the values without a temporary variable.

Answer

a = b; b = a

Answer

a = a ^ b; b = a ^ b; a = a ^ b

Answer

a = b + a; b = a - b; a = a - b

Question 7

What is the output of the code?

Accepted Answer

0 1 2 4. The code uses a for loop with range(5) to iterate over numbers 0 through 4. Inside the loop, an if statement checks if the current number equals 3; if true, the break statement exits the loop immediately. Therefore, when i becomes 3, the loop terminates before printing 3, so the output is '0 1 2' (each on a new line due to print(i) default behavior). Option C correctly lists the printed values as 0, 1, 2, and then 4 is not printed because the loop breaks before reaching 4.

Answer

No output

Answer

0 1 2 3 4

Answer

0 1 2 4 5

Question 8

A programmer writes code that uses a while loop to process user input until the user types 'exit'. The code currently prints 'Done' after the loop, but it never exits. What is the most likely cause?

Accepted Answer

The variable controlling the loop is not updated inside the loop. Option D is correct because if the variable controlling the loop (e.g., the user's input) is never updated inside the while loop, the loop condition will never become false, causing an infinite loop. In this scenario, the programmer likely reads input once before the loop but does not call input() again inside the loop to update the variable, so the loop never sees the 'exit' value.

Answer

The loop condition is 'while True'

Answer

The print statement is indented incorrectly

Answer

The input function is called outside the loop

Question 9

A developer runs main.py and gets True. They then modify config.py by adding `allowed_ports.append(22)` and run main.py again without restarting the interpreter. What is the output?

Accepted Answer

True. Option D is correct because Python imports modules only once per interpreter session; subsequent imports use the cached module object. Since `config.py` was already imported, modifying the file does not affect the already-loaded list object in memory. The `allowed_ports` list remains unchanged, so the condition that originally returned `True` still holds.

Answer

False

Answer

None

Answer

Error

Question 10

Which TWO of the following code snippets will print the numbers 0, 1, 2, 3, 4?

Accepted Answer

for i in range(0,5): print(i). Option A is correct because `range(0,5)` generates the sequence 0, 1, 2, 3, 4. The `range()` function with two arguments (start, stop) produces numbers from start inclusive up to, but not including, stop. Therefore, iterating with `for i in range(0,5): print(i)` prints exactly 0 through 4.

Answer

for i in range(5+1): print(i)

Answer

for i in range(0,5,2): print(i)

Answer

for i in range(1,6): print(i)