PCEP Control Flow, Loops, Lists and Logic Practice Test 5 — 15 Questions

Question 1

You are working on a network automation script that reads a configuration file containing firewall rules. Each rule is a dictionary with keys 'source_ip', 'dest_ip', 'action'. The script must iterate over the rules and print all rules where action is 'allow'. However, the script is not printing any output even though there are allow rules in the file. The code snippet is:

rules = [{'source_ip':'10.0.0.1','dest_ip':'10.0.0.2','action':'allow'},
         {'source_ip':'10.0.0.2','dest_ip':'10.0.0.3','action':'deny'}]
for rule in rules:
    if rule('action') == 'allow':
        print(rule)

What is the most likely cause of the problem?

Accepted Answer

The developer used rule('action') instead of rule['action']. In Python, dictionary values are accessed using square brackets (e.g., rule['action']) or the .get() method, not parentheses. Using parentheses like rule('action') attempts to call the dictionary as a function, which raises a TypeError and prevents the script from executing, so no output is printed even though allow rules exist.

Answer

The dictionary does not have an 'action' key

Answer

The developer used rule['action'] instead of rule.get('action')

Answer

The for loop syntax is incorrect; it should be for rule in rules:

Question 2

Arrange the steps to handle an exception in Python using try-except.

Accepted Answer

try block, then except block, then else block, then finally block. Exception handling wraps risky code in try, catches exceptions with except, and optionally includes else and finally.

Answer

try block, then except block, then finally block, then else block

Answer

try block, then else block, then except block, then finally block

Answer

except block, then try block, then else block, then finally block

Question 3

Arrange the steps to install a third-party Python package using pip.

Accepted Answer

1. Ensure pip is installed. 2. Run 'pip install package_name'. 3. Verify the installation by importing the package in Python.. Installing packages with pip involves checking pip, running install, and verifying.

Answer

1. Run 'pip install package_name'. 2. Check if pip is installed. 3. Verify the installation.

Answer

1. Verify the installation by importing the package. 2. Ensure pip is installed. 3. Run 'pip install package_name'.

Answer

1. Download the package manually from a website. 2. Run 'pip install' with the downloaded file. 3. Check pip version.

Question 4

A developer needs to iterate over a list of network interfaces and print only the names that start with 'eth'. Which code should be used?

Accepted Answer

for iface in interfaces: if iface.startswith('eth'): print(iface). The `startswith()` string method is the most direct and readable way to check if each interface name begins with the substring 'eth'. This approach avoids unnecessary slicing or substring membership checks, making the intent clear and the code efficient.

Answer

for i in range(len(interfaces)): if 'eth' in interfaces[i]: print(interfaces[i])

Answer

for iface in interfaces: if iface[:3] is 'eth': print(iface)

Answer

for iface in interfaces: if 'eth' in iface: print(iface)

Question 5

A programmer has a list of tuples representing (product, price) and wants to find the highest price. Which code correctly finds the maximum price?

Accepted Answer

max_price = max([price for product, price in prices]). Ly uses a list comprehension to extract all prices from the tuples, then passes that list to the built-in `max()` function, which returns the highest numeric value. This directly solves the problem of finding the maximum price without any unnecessary complexity.

Answer

max_price = max(prices, key=lambda x: x[1])

Answer

max_price = 0; for p in prices: if p[1] > max_price: max_price = p[1]

Answer

max_price = sorted(prices, key=lambda x: x[1])[-1]

Question 6

Which code correctly creates a list of squares for numbers 1 to 5 using a list comprehension?

Accepted Answer

squares = [x**2 for x in range(1,6)]. It uses the proper syntax for a list comprehension: `[expression for item in iterable]`. Here, `x**2` computes the square, and `range(1,6)` generates numbers 1 through 5 (since range excludes the stop value). This produces the list `[1, 4, 9, 16, 25]`.

Answer

squares = [x**2 for x in range(5)]

Answer

squares = [x^2 for x in (1,2,3,4,5)]

Answer

squares = [x^2 for x in [1,2,3,4,5]]

Question 7

A developer needs to implement a loop that prints numbers from 10 down to 1. Which loop correctly achieves this?

Accepted Answer

for i in range(10, 0, -1): print(i). `range(10, 0, -1)` generates numbers from 10 down to 1 inclusive. The start is 10, the stop is 0 (exclusive), and the step is -1, so the sequence is 10, 9, 8, ..., 1. This matches the requirement exactly.

Answer

for i in range(10, 0): print(i)

Answer

for i in reversed(range(1, 10)): print(i)

Answer

for i in range(10, 1, -1): print(i)

Question 8

A program contains a nested while loop. The inner loop should run as long as a condition is True, but the outer loop should stop after 3 iterations. Which code structure is correct? (Assume the inner loop condition is inner < 5.)

Accepted Answer

outer = 0
while outer < 3:
    inner = 0
    while inner < 5:
        # do something
        inner += 1
    outer += 1. Ly implements a nested while loop where the inner loop runs while `inner < 5` and the outer loop runs while `outer < 3`. The inner loop increments `inner` to control its own termination, and the outer loop increments `outer` after the inner loop completes, ensuring exactly 3 iterations of the outer loop. This matches the requirement that the outer loop stops after 3 iterations while the inner loop runs as long as its condition is True.

Answer

for outer in range(3):
    inner = 0
    while inner < 5:
        # do something
        inner += 1

Answer

outer = 0
while outer < 3:
    for inner in range(5):
        # do something
        outer += 1

Answer

outer = 0
while outer < 3:
    inner = 0
    while inner < 5:
        # do something
        outer += 1
        inner += 1

Question 9

Which two of the following list methods modify the original list in place? (Choose two.)

Accepted Answer

sort(). Option A, sort(), is correct because it is a list method that reorders the list's elements directly in the existing list object and returns None, so the original list is modified in place. Option D, append(), is correct because it adds a single element to the end of the existing list object and also returns None, mutating the original list. Option B, count(), is not correct because it only returns the number of occurrences of a value and does not change the list. Option C, sorted(), is not correct because it is a built-in function that returns a new sorted list, leaving the original list unchanged. Option E, copy(), is not correct because it returns a shallow copy of the list without modifying the original list.

Answer

count()

Answer

sorted()

Answer

copy()

Question 10

Which three of the following statements about lists are true? (Choose three.)

Accepted Answer

Lists can be indexed with integers.. Lists in Python are ordered sequences that support indexing with integers, starting from 0 for the first element and negative integers for reverse indexing. This allows direct access to any element by its position, a fundamental feature of sequence types in Python.

Answer

Lists have a fixed size once created.

Answer

Lists can only contain elements of the same data type.

Question 11

What is the output of the following code?

numbers = [1, 2, 3, 4, 5]
total = 0
for i in numbers:
    if i % 2 == 0:
        continue
    total += i
print(total)

Accepted Answer

9. The exhibit shows code that iterates over the list [1, 2, 3, 4, 5] and uses `if i % 2 == 0: continue` to skip even numbers. Only odd numbers (1, 3, 5) are summed, giving 1 + 3 + 5 = 9. Therefore, option D is correct.

Answer

10

Answer

8

Answer

6

Question 12

What is the output of the following code?

for i in range(1, 6):
    if i == 3:
        continue
    print(i, end=' ')

Accepted Answer

1 2 4 5. The code uses a for loop with range(1, 6) and a continue statement when i == 3. When i equals 3, the continue skips the print(i, end=' ') statement, so 3 is not printed. The loop iterates through 1, 2, 4, and 5, producing the output '1 2 4 5'.

Answer

1 2 3 4 5

Answer

1 2 4

Answer

1 2 3 4

Question 13

A company maintains a list of employee names. They want to check if 'Alice' is in the list. Which of the following is the most Pythonic way to achieve this?

Accepted Answer

if 'Alice' in employees:. The most Pythonic way because it uses the `in` operator, which directly checks membership in a list with a single, readable expression. This approach is idiomatic Python, leveraging the language's built-in support for membership testing without manual iteration or exception handling.

Answer

employees.contains('Alice')

Answer

for name in employees: if name == 'Alice': found = True; break

Answer

if employees.index('Alice') != -1:

Question 14

A developer writes a while loop to count down from 10 to 1 and then stop. Which condition should be used?

Accepted Answer

while counter > 0:. The while loop must continue as long as the counter is greater than 0, counting down from 10 to 1. When counter becomes 0, the condition `counter > 0` evaluates to False, and the loop terminates, stopping exactly at 1.

Answer

while counter != 0:

Answer

while counter >= 0:

Answer

while counter < 10:

Question 15

A team is reviewing code that uses if-elif-else to classify a test score. They notice that for score 90, it prints 'B' instead of 'A'. Which of the following best explains the issue?

Accepted Answer

The condition for 'A' should be checked before 'B'. In an if-elif-else chain, the first matching condition is executed and the rest are skipped. If the condition for 'A' (e.g., score >= 90) is placed after the condition for 'B' (e.g., score >= 80), a score of 90 will match the 'B' condition first and never reach the 'A' condition. To fix this, the most restrictive condition (highest grade) must be checked first.

Answer

The order of conditions does not matter

Answer

The elif condition should use >= instead of >

Answer

The code uses elif instead of else if