Hackerrank - HackerRank Python Scalar Types and Operators Questions and Answers 1 — Questions and Answers
Question 1: What is the output of the following Python code snippet? x = 15 y = 4 result = x // y + (x % y) print(result)
- 6 (Correct answer)
- 7
- 3.75
- A TypeError occurs
Correct answer: 6
The floor division operator `//` calculates the quotient, discarding the remainder. `15 // 4` results in `3`. The modulo operator `%` calculates the remainder of the division. `15 % 4` results in `3`. The expression then becomes `3 + 3`, which equals `6`.
Question 2: Which of the following correctly describes the `None` object in Python?
- It is equivalent to an empty string `''` or the integer `0`.
- It is a keyword used to signify the absence of a value and its type is `NoneType`. (Correct answer)
- It is a placeholder for variables that will be assigned a string value later.
- It is a mutable object that can be changed to any other data type.
Correct answer: It is a keyword used to signify the absence of a value and its type is `NoneType`.
In Python, `None` is a special constant that represents the absence of a value or a null value. It is not the same as `0`, `False`, or an empty string. `None` is the sole value of the `NoneType` data type, and it is immutable.
Question 3: A developer needs to ensure a function is only called if a list is not empty to avoid an `IndexError`. Which code snippet uses short-circuiting to achieve this safely? `my_list = []` `def process_list(data): print(data[0])`
- `if my_list and process_list(my_list): pass` (Correct answer)
- `if process_list(my_list) and my_list: pass`
- `if len(my_list) > 0 or process_list(my_list): pass`
- `if not my_list and process_list(my_list): pass`
Correct answer: `if my_list and process_list(my_list): pass`
The `and` operator in Python uses short-circuit evaluation. It evaluates the expression from left to right. If the first operand (`my_list`) is falsy (an empty list is falsy), it stops and does not evaluate the second operand (`process_list(my_list)`), thus preventing the `IndexError`. The other options would either still call the function or use incorrect logic.
Question 4: What is the value of the variable `z` after this code executes? `z = 10 + 4 * 2 ** 3 / 8 - 1`
- 14.0
- 13.0 (Correct answer)
- 5.0
- 27.0
Correct answer: 13.0
Python follows the PEMDAS/BODMAS order of operations. The exponentiation `2 ** 3` is calculated first (8). Then, multiplication and division are performed from left to right: `4 * 8` is 32, and `32 / 8` is 4.0. Finally, addition and subtraction are performed: `10 + 4.0` is 14.0, and `14.0 - 1` is 13.0.
Question 5: In Python, boolean values `True` and `False` are instances of which scalar type?
- `int`
- `str`
- `bool` (Correct answer)
- `object`
Correct answer: `bool`
The values `True` and `False` are literals of the `bool` data type. While they can behave like the integers `1` and `0` in arithmetic contexts, their fundamental type is `bool`.
Question 6: Given the expression `result = 5 > 3 < 4`, what is the final value of `result`?
- True (Correct answer)
- False
- An error is raised
- 1
Correct answer: True
Python allows for chaining comparison operators. The expression `5 > 3 < 4` is evaluated as `(5 > 3) and (3 < 4)`. Both of these comparisons are `True`, and `True and True` results in `True`.
Hackerrank - HackerRank Python Scalar Types and Operators Questions and Answers 1
What is the output of the following Python code snippet?
x = 15
y = 4
result = x // y + (x % y)
print(result)