PCEP Control Flow, Loops, Lists and Logic Practice Test 8 — 15 Questions

Question 1

Refer to the exhibit. What does the else clause of the inner for loop do?

Accepted Answer

Executes if the inner loop completes without break, meaning no even number in the row.. The else clause of a for loop in Python executes only when the loop completes normally, i.e., without encountering a break statement. In this nested loop, the inner for iterates over elements of a row; if no even number is found (no break), the else triggers, indicating the row has no even numbers. This is why option C is correct.

Answer

Executes if the outer loop condition is false.

Answer

Executes if the inner loop is broken, meaning an even number was found.

Answer

Executes after each iteration of the inner loop.

Question 2

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

Accepted Answer

1 2 4 5. The code uses a for loop with range(1,6) to iterate over numbers 1 through 5. Inside the loop, an if statement checks if the current number equals 3; if true, the continue statement skips the print(i) for that iteration. Thus, when i is 3, the print is skipped, so the output is '1 2 4 5'. Option B is correct because it matches this output.

Answer

0 1 2 4 5

Answer

1 2 3 4 5

Answer

2 4 5

Question 3

A developer needs to iterate over a list named `colors` and print each color on a separate line. Which code snippet correctly accomplishes this?

Accepted Answer

for color in colors:
    print(color). The correct way to iterate over a list and print each element is to use a for loop with proper indentation and a colon at the end of the loop header. The loop variable takes each element from the list in turn, and the indented block executes for each element. This pattern is fundamental in Python for processing sequences.

Answer

for (color in colors):
    print(color)

Answer

for color in colors:
print(color)

Answer

for color in colors
    print(color)

Question 4

A programmer is writing a script to process a list of sensor readings. The script should stop processing as soon as a reading of 0 is encountered. Which statement should be placed inside the loop to achieve this?

Accepted Answer

break. To stop a loop immediately when a condition is met, the `break` statement is used. It transfers control to the statement immediately following the loop. The `continue` statement would only skip the current iteration, while `pass` does nothing and `exit` is not a valid loop control statement.

Answer

exit

Answer

pass

Answer

continue

Question 5

A developer is debugging a script that uses a `while` loop to process items from a queue. The loop is intended to run until the queue is empty, but the script hangs indefinitely. Which of the following is the most likely cause?

Accepted Answer

The loop condition never becomes false because the queue is not being modified inside the loop.. An infinite `while` loop occurs when the loop condition never evaluates to false. If the queue is not being emptied, the condition `while queue:` remains true. The loop body must include an operation that removes items from the queue, such as `pop()` or `popleft()`, to eventually make the condition false and terminate the loop.

Answer

The `break` statement is missing from the loop body.

Answer

The loop uses `continue` instead of `break`.

Answer

The queue is a list, and lists cannot be used in `while` conditions.

Question 6

A Python developer is writing a script that processes a list of sensor readings stored in the variable readings. The developer needs to iterate over the list and print each reading, but wants the loop to stop immediately if a reading of -999 is encountered, because that value indicates a sensor malfunction. Which code snippet correctly implements this behavior?

Accepted Answer

for reading in readings:
    if reading == -999:
        break
    print(reading). The correct implementation must iterate over the list, check for the malfunction value, and break immediately without printing that value. The snippet that places the break inside the if block and the print after the if block ensures that normal readings are printed and the loop terminates upon encountering -999. This matches the specified behavior precisely.

Answer

for reading in readings:
    if reading != -999:
        print(reading)
    else:
        break

Answer

for reading in readings:
    print(reading)
    if reading == -999:
        break

Answer

for reading in readings:
    if reading == -999:
        continue
    print(reading)

Question 7

A logistics analyst is writing a Python script that processes a list of shipment weights in kilograms. The analyst needs to display each weight one at a time and also know its position in the list, starting from 1 rather than 0. Which approach most directly accomplishes this?

Accepted Answer

Use for index, weight in enumerate(weights, start=1): and print index and weight.. The enumerate() function is designed to pair each element of an iterable with a counter. Supplying start=1 shifts the counter so the first shipment is numbered 1. Other approaches either produce 0-based indexes, mutate the list, or require manual offset adjustments that are easy to get wrong.

Answer

Use for i in range(len(weights)): and print i and weights[i].

Answer

Use for weight in weights: and print weights.index(weight).

Answer

Use while weights: and pop the first element each time, printing its value.

Question 8

A Python programmer is analyzing a list of integers named numbers. The programmer wants to create a new list that contains only the even numbers from numbers, each multiplied by 10. Which two of the following code snippets correctly produce the desired list? (Choose two.)

Accepted Answer

result = []
for n in numbers:
    if n % 2 == 0:
        result.append(n * 10). The desired output requires filtering even numbers and then multiplying each by 10. The explicit for-loop with append and the list comprehension both correctly perform this filter-and-transform operation. The other options either select odd numbers, fail to multiply, or multiply the list itself instead of its elements.

Answer

result = [n * 10 for n in numbers if n % 2 != 0]

Answer

result = []
for n in numbers:
    if n % 2 == 0:
        result.append(n)
        n = n * 10

Answer

result = [n for n in numbers if n % 2 == 0] * 10

Question 9

A Python developer is writing a program that prompts the user to enter a positive integer. The program should repeatedly ask for input until the user enters a number greater than zero. Which loop construct is most appropriate to implement this requirement?

Accepted Answer

while loop with a condition. The requirement is to repeatedly prompt the user until a positive integer is entered. This calls for a loop that continues based on a condition that depends on user input. A while loop is designed for such indefinite iteration, as it checks the condition before each iteration and can be controlled by the input value. Other constructs either cannot repeat indefinitely or do not exist in Python.

Answer

for loop with a range

Answer

if statement with a break

Answer

do-while loop

Question 10

An inventory script stores product quantities in a list named stock. The script must print the running total of quantities from the start of the list up to, but not including, the first zero quantity it encounters. Which code fragment produces this behavior?

Accepted Answer

total = 0
for q in stock:
    if q == 0:
        break
    total += q
print(total). The requirement is to accumulate quantities until the first zero appears, then stop without adding that zero. Placing the zero test before the addition and exiting with break achieves exactly this, because the loop terminates before the zero can be added to the running total.

Answer

total = 0
for q in stock:
    total += q
    if q == 0:
        break
print(total)

Answer

total = 0
for q in stock:
    if q == 0:
        continue
    total += q
print(total)

Answer

total = 0
for q in stock:
    total += q
    if q == 0:
        continue
print(total)

Question 11

A teacher writes a program that must print each student name from a list called roster on its own line, but stop printing entirely as soon as the name "STOP" is encountered, without printing "STOP" itself. Which loop body achieves this?

Accepted Answer

for name in roster:
    if name == "STOP":
        break
    print(name). Placing the sentinel comparison before the print call and using break ensures the loop terminates at the first occurrence of "STOP" without emitting that value. Checking after printing would leak the sentinel into the output, and using continue would skip only one element while later names still print, so only the pre-check with break satisfies both conditions.

Answer

for name in roster:
    while name != "STOP":
        print(name)
        break

Answer

for name in roster:
    print(name)
    if name == "STOP":
        break

Answer

for name in roster:
    if name == "STOP":
        continue
    print(name)

Question 12

A Python programmer is working with a list of strings called words. The programmer wants to create a new list that contains the lengths of each word, but only for words that have more than three characters. Which code snippet correctly produces this list?

Accepted Answer

lengths = [len(word) for word in words if len(word) > 3]. The correct snippet must filter words with more than three characters and then transform each remaining word into its length. The list comprehension that uses len(word) in the expression and filters with len(word) > 3 accomplishes both steps correctly. Other options either compare the wrong types, return the wrong data, or incorrectly append both words and lengths.

Answer

lengths = []
for word in words:
    if len(word) > 3:
        lengths.append(word)
    lengths.append(len(word))

Answer

lengths = [word for word in words if len(word) > 3]

Answer

lengths = [len(word) for word in words if word > 3]

Question 13

A logistics coordinator stores shipment weights in a list `weights = [12, 18, 7, 25]`. She needs to find the average weight of all shipments. Which code snippet correctly computes and prints the average?

Accepted Answer

print(sum(weights) / len(weights)). The average is calculated by dividing the sum of all elements by the number of elements. The built-in `sum()` and `len()` functions provide these values directly, and the `/` operator returns a float result. The other options either use incorrect functions or perform integer division, which loses the fractional part.

Answer

print(total(weights) / len(weights))

Answer

print(mean(weights) / len(weights))

Answer

print(sum(weights) // len(weights))

Question 14

A logistics analyst maintains a list `weights` representing the mass of parcels in kilograms. The analyst needs to determine how many parcels weigh more than 10 kg, but the list also contains a few `None` values that indicate missing measurements and must not be counted. Which code correctly counts only the parcels heavier than 10 kg while ignoring missing entries?

Accepted Answer

count = 0
for w in weights:
    if w is not None and w > 10:
        count += 1. The correct code uses a combined condition that first verifies the element is not None, then compares it with 10. This ordering exploits short-circuit evaluation so that None never reaches the numeric comparison. As a result, only actual numeric weights greater than 10 increment the counter, and missing measurements are silently skipped as required by the analyst.

Answer

count = 0
for w in weights:
    if w > 10:
        count += 1

Answer

count = sum(1 for w in weights if w > 10)

Answer

count = 0
for w in weights:
    if w > 10 or w is None:
        count += 1

Question 15

A developer is writing a Python script that must iterate over the characters of the string stored in variable `word` and print each character on its own line, without using index numbers. Which of the following loops accomplishes this?

Accepted Answer

for ch in word:
    print(ch). A Python `for` loop iterates directly over any iterable object, and strings are iterables that produce their characters one at a time. Binding each character to a loop variable and printing it yields exactly one character per line in the original order. The remaining constructs either iterate over numeric indexes, never advance the loop variable, or split the string into words rather than characters.

Answer

while word:
    print(word)

Answer

for ch in word.split():
    print(ch)

Answer

for ch in range(len(word)):
    print(ch)