PCEP Data Types, Variables, Basic I/O and Operators Practice Test 13 — 15 Questions

Question 1

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 2

Which three of the following are Python arithmetic operators? (Choose three.)

Accepted Answer

+. The plus sign (+) is a standard Python arithmetic operator used for addition. It performs numeric addition when both operands are numbers, and also supports string concatenation, but its primary role in arithmetic contexts is addition.

Answer

|

Answer

&

Question 3

A beginner writes: x = 10; y = "20"; print(x + y). What will happen?

Accepted Answer

It raises a TypeError. Python does not allow implicit type conversion between a string and an integer in an addition operation. The `+` operator with a string and an integer raises a `TypeError`, as Python's dynamic typing requires explicit conversion (e.g., `int(y)` or `str(x)`) for such mixed-type operations.

Answer

It prints 30 as a string

Answer

It prints 1020

Answer

It prints 30

Question 4

A program calculates BMI. User inputs weight and height as strings. Which line correctly converts to float?

Accepted Answer

weight = float(input()). `float(input())` first reads the user's input as a string via `input()`, then converts that string to a floating-point number using the `float()` function. This is the standard Python pattern for converting user input to a numeric type.

Answer

weight = float(input)

Answer

weight = input().float()

Answer

weight = input(float())

Question 5

After executing: a = 5; b = 2; c = a // b; d = a % b; e = a ** b. What is the value of (c + d) * 2 - e?

Accepted Answer

-19. After executing the code, a=5, b=2, c=5//2=2 (floor division), d=5%2=1 (remainder), e=5**2=25 (exponentiation). Then (c+d)*2-e = (2+1)*2-25 = 3*2-25 = 6-25 = -19. Option B is correct because it matches this calculation.

Answer

-20

Answer

-11

Answer

-15

Question 6

Which of the following is NOT a valid variable name in Python?

Accepted Answer

2nd_var. Python variable names cannot start with a digit. The name '2nd_var' begins with '2', which violates Python's identifier naming rules. Valid variable names must start with a letter (a-z, A-Z) or an underscore (_), and can be followed by letters, digits, or underscores.

Answer

_myvar

Answer

myVar2

Answer

my_var

Question 7

A developer needs to read an integer from user input and store it. Which code snippet accomplishes this?

Accepted Answer

x = int(input()). `int(input())` first calls `input()` to read a string from the user, then passes that string to `int()` to convert it to an integer. This is the standard Python pattern for reading an integer from standard input.

Answer

x = read_int()

Answer

x = input(int())

Answer

x = int(input)

Question 8

What is the output of the following code? print(type(3.0) == float)

Accepted Answer

True. The expression `type(3.0) == float` compares the result of `type(3.0)` (which is `<class 'float'>`) directly to the `float` class. In Python, `type()` returns the class object, and comparing it with `==` to the built-in class `float` yields `True` because they are the same object. Therefore, `print(True)` outputs `True`.

Answer

Answer

False

Answer

Error

Question 9

Which operator is used for integer division in Python?

Accepted Answer

//. The // operator in Python performs floor division, which returns the integer quotient after dividing two numbers, discarding any fractional remainder. For example, 7 // 2 yields 3, not 3.5, making it the explicit integer division operator.

Answer

%

Answer

**

Answer

/

Question 10

A program prints a greeting: name = input("Enter name: "); print("Hello, " + name + "!"). If user enters "Alice", what is output?

Accepted Answer

Hello, Alice!. The `print` function concatenates the string literals and the variable `name` using the `+` operator exactly as specified. When the user enters "Alice", the expression `"Hello, " + name + "!"` becomes `"Hello, Alice!"` — the space after the comma is part of the first string literal, and the exclamation mark is part of the last string literal, producing the output exactly as shown in option A.

Answer

Hello,Alice !

Answer

Hello,Alice!

Answer

Hello, Alice !

Question 11

Consider: x = True; y = False; z = x and not y or x. What is the value of z?

Accepted Answer

True. The expression `x and not y or x` is evaluated with operator precedence: `not` has the highest precedence, then `and`, then `or`. Given `x = True` and `y = False`, `not y` evaluates to `True`. Then `x and True` is `True and True`, which is `True`. Finally, `True or x` (where `x` is `True`) short-circuits to `True`. Thus, `z` is `True`.

Answer

None

Answer

Error

Answer

False

Question 12

Which THREE of the following expressions evaluate to the integer 1? (Select three.)

Accepted Answer

int(1.0). Option A, int(1.0), is correct because Python's int() constructor truncates the float 1.0 toward zero, yielding the integer 1. Option B, 2 // 2, is correct because floor division of 2 by 2 produces the integer quotient 1. Option E, 4 % 3, is correct because the modulo operator returns the remainder of 4 divided by 3, which is the integer 1. Option C, True == 1, evaluates to the Boolean True rather than the integer 1, even though True is numerically equal to 1 in Python. Option D, 1 * 1.0, evaluates to the float 1.0, not the integer 1, because multiplying an int by a float promotes the result to float.

Answer

True == 1

Answer

1 * 1.0

Question 13

Which TWO of the following expressions evaluate to 0? (Select two.)

Accepted Answer

False * 1. In Python, False is a bool that behaves as the integer 0 in arithmetic, so 0 * 1 evaluates to 0. Option D (int(0.5)) is correct because int() truncates toward zero, discarding the fractional part of 0.5 and returning 0. Option B (5 // 2 * 2) evaluates to 4, since floor division 5 // 2 gives 2 and 2 * 2 is 4, not 0. Option C (True == 0) evaluates to False, because True equals 1, not 0. Option E (5 % 2) evaluates to 1, the remainder of 5 divided by 2, so it is not 0.

Answer

5 // 2 * 2

Answer

True == 0

Answer

5 % 2

Question 14

A program asks for the user's age and then prints a message: age = input("How old are you? "); print("You are " + age + " years old."). A user enters "twenty five" and the program prints "You are twenty five years old." which is not the intended numeric age. The requirement is to ensure only numeric ages are accepted and to convert the input to an integer. Which modification is the best?

Accepted Answer

Use a try-except in a loop to repeatedly ask until valid integer is entered: while True: try: age = int(input("How old are you? ")) break except ValueError: print("Invalid."). It uses a `while True` loop with a `try-except` block to repeatedly prompt the user until a valid integer is entered. The `int()` conversion raises a `ValueError` for non-numeric strings like "twenty five", and the `except` clause catches that error and prints "Invalid." without breaking the loop, ensuring only numeric ages are accepted and converted to an integer.

Answer

Use try-except to catch ValueError and print an error message, then exit.

Answer

Check if age.isdigit() before converting, and if not, ask again.

Answer

Assume the user will always enter a number; no changes needed.

Question 15

A company needs to calculate the average of three test scores entered by a user. The scores are integers. The programmer writes the following code:

s1 = input("Enter score 1: ")
s2 = input("Enter score 2: ")
s3 = input("Enter score 3: ")
avg = (s1 + s2 + s3) / 3
print("Average:", avg)

When run, the output is incorrect. What is the most likely cause?

Accepted Answer

The input() function returns strings, so concatenation occurs instead of addition.. The `input()` function in Python always returns a string, even when the user types numbers. The `+` operator on strings performs concatenation (e.g., '5' + '3' + '2' becomes '532'), not numeric addition. Dividing the concatenated string by 3 then causes a `TypeError` (or produces an incorrect result if the string is implicitly converted), so the average calculation fails.

Answer

The division by 3 will cause a ZeroDivisionError because 3 is not a float.

Answer

The division operator / always returns an integer, but the sum is not an integer.

Answer

The variable names s1, s2, s3 are not allowed because they start with a letter.