PCEP Practice Test 5 — 10 Questions

Question 1

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?

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

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 2

A developer needs to swap the values of two variables a and b without using a temporary variable. Which single line of code correctly performs the swap?

Accepted Answer

a, b = b, a. Python supports tuple unpacking, which allows swapping the values of two variables in a single line without a temporary variable. The expression `a, b = b, a` evaluates the right-hand side tuple `(b, a)` first, then assigns the values to `a` and `b` respectively, effectively swapping them. Option A fails because after `a = b`, the original value of `a` is lost, so `b = a` assigns the same value to both. Option C (XOR swap) works but requires three statements, not a single line. Option D (arithmetic swap) also works but requires three statements and may cause overflow in other languages, though Python handles big integers; still, it is not a single line.

Answer

a = b; b = a

Answer

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

Answer

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

Question 3

Which of the following best describes the behavior of the 'range' function in a for loop?

Accepted Answer

It generates a sequence of numbers from start to stop exclusive. The built-in `range()` function in Python generates an immutable sequence of numbers from the start value (default 0) up to, but not including, the stop value. When used in a `for` loop, it yields each number in the sequence one at a time, making it ideal for iterating a fixed number of times. The stop value is exclusive, meaning the loop body does not execute for the stop value itself.

Answer

It returns a list of numbers with a default step of 0

Answer

It can only be used with integers

Answer

It generates a list of numbers from start to stop inclusive

Question 4

What is the output of the following code?
print(3 * 'ab' + 'c')

Accepted Answer

'abababc'. The expression `3 * 'ab' + 'c'` first multiplies the string `'ab'` by 3, resulting in `'ababab'` (string repetition), and then concatenates `'c'` using the `+` operator, producing `'abababc'`. In Python, the `*` operator on a string and an integer repeats the string that many times, and `+` concatenates strings.

Answer

'ababc'

Answer

TypeError

Answer

'ababab c'

Question 5

A program contains this code: print(1 and 2 or 3). What is the output?

Accepted Answer

2. In Python, the `and` and `or` operators short-circuit and return the last evaluated operand, not a boolean. `1 and 2` evaluates to `2` because both are truthy and `and` returns the last truthy value. Then `2 or 3` short-circuits because `2` is truthy, so `or` returns `2` without evaluating `3`. Thus, the output is `2`.

Answer

3

Answer

1

Answer

True

Question 6

A data analyst writes a Python script to double each element in a matrix without altering the original. The code is:

original = [[1,2,3],[4,5,6]]
copy = original
for i in range(len(original)):
    for j in range(len(original[i])):
        copy[i][j] *= 2
print(original)

The output shows [[2,4,6],[8,10,12]], meaning the original was also changed. Which single modification to the line 'copy = original' ensures the original matrix remains unchanged?

Accepted Answer

Replace `copy = original` with `import copy; copy = copy.deepcopy(original)`. `copy.deepcopy()` creates a fully independent copy of the nested list structure. In Python, assignment (`copy = original`) only copies the reference to the outer list, so modifying elements through `copy` also modifies `original`. Shallow copies (like `original[:]` or `list(original)`) copy the outer list but still share references to the inner lists, so changes to inner elements affect both. Only `deepcopy` recursively duplicates all nested objects, ensuring the original matrix remains unchanged.

Answer

Replace `copy = original` with `copy = original[:]`

Answer

Replace `copy = original` with `copy = list(original)`

Answer

Replace the nested loop with a list comprehension: `copy = [[x*2 for x in row] for row in original]`

Question 7

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

Question 8

What does the following code output? for i in range(3): if i == 1: continue; print(i, end=' ')

Accepted Answer

0 2. The for loop iterates over range(3), which produces values 0, 1, and 2. When i equals 1, the continue statement skips the rest of the loop body for that iteration, so print(i, end=' ') is not executed for i=1. Thus, only 0 and 2 are printed, separated by a space, giving output '0 2'. Option B is correct.

Answer

1

Answer

0 1 2

Answer

0

Question 9

A developer writes code to calculate the area of a rectangle and prints it. The code is:
length = 10
width = 5
area = length + width
print('The area is', area)
If the width is accidentally assigned a string '5', what error will occur?

Accepted Answer

TypeError. In Python, adding an integer and a string is not a valid operation; it will raise a TypeError because Python cannot implicitly convert the string to an integer for arithmetic. Therefore, the code will raise a TypeError when executed.

Answer

ValueError

Answer

SyntaxError

Answer

NameError

Question 10

Which two of the following are valid ways to create a list with elements 1, 2, 3? (Select two.)

Accepted Answer

list = list(range(1, 4)). `list(range(1, 4))` creates a list from the range object that generates numbers 1, 2, and 3 (the `range` function stops before the stop value 4). This is a common Python idiom for converting a range into a list.

Answer

list = [1, 2, 3]]

Answer

list = (1, 2, 3)

Answer

list = [1; 2; 3]