Python Quiz

1. How does Python mark which lines belong to an if block?

• Curly braces
• The end keyword
• Indentation
• Semicolons

Indentation is part of Python's syntax (lesson 03).

2. What is the naming convention for variables and functions in Python?

• camelCase
• snake_case
• PascalCase
• kebab-case

PEP 8 uses snake_case for variables and functions (lessons 04 and 54).

3. What does 7 / 2 return?

• 3
• 3.5
• 4
• "3.5"

/ always returns a float; use // for floor division (lessons 06 and 12).

4. What does "5" + 3 do?

• Returns 8
• Returns "53"
• Raises a TypeError
• Returns None

Python doesn't implicitly convert between strings and numbers (lesson 05).

5. What does int("3.5") do?

• Returns 3
• Returns 4
• Raises a ValueError
• Returns 3.5

Convert via float first: int(float("3.5")) (lesson 07).

6. What is "Python"[-1]?

• "P"
• "n"
• "o"
• An error

Negative indexes count from the end (lesson 08).

7. What does f"{3.14159:.2f}" produce?

• "3.14"
• "3.1"
• "3.14159"
• "03.14"

.2f means two decimal places (lesson 10).

8. Which value is truthy?

• 0
• ""
• []
• "0"

Any non-empty string is truthy (lesson 11).

9. What's the correct way to check for None?

• if x == None:
• if x is None:
• if x = None:
• if None(x):

None is a singleton; compare with is (lesson 11).

10. What does 1 < x < 10 mean in Python?

• 1 < x and x < 10
• (1 < x) < 10, comparing a boolean to 10
• A syntax error
• 1 < x or x < 10

Python supports chained comparisons (lesson 12).

11. What does input() always return?

• An int
• A string
• Whatever type the user typed
• None

Convert with int() or float() when you need a number (lesson 13).

12. In a match statement, what does a bare name like case x: do?

• Compares with a variable named x
• Captures any value into a variable named x
• Raises an error
• Matches only the string "x"

Bare names capture; use literals or dotted names to compare (lesson 15).

13. What does list(range(2, 8, 2)) produce?

• [2, 4, 6, 8]
• [2, 4, 6]
• [2, 8]
• [0, 2, 4, 6]

The stop value is never included (lesson 17).

14. When does a loop's else block run?

• When the loop body raises an error
• On every iteration
• When the loop finishes without hitting break
• Never in for loops

Think of it as "no break" (lesson 18).

15. What does nums.sort() return?

• The sorted list
• None — it sorts in place
• A new sorted copy
• The number of items

Use sorted(nums) for a new list (lesson 20).

16. What does [n * 2 for n in range(4) if n % 2 == 0] produce?

• [0, 4]
• [0, 2, 4, 6]
• [2, 6]
• [0, 1, 2, 3]

Keeps 0 and 2, then doubles them (lesson 21).

17. How do you write a tuple with one item?

• (42)
• (42,)
• [42]
• tuple 42

The comma makes the tuple (lesson 22).

18. Which can be used as a dictionary key?

• A list
• A dictionary
• A set
• A tuple of numbers

Keys must be hashable (immutable) (lessons 22–24).

19. What does {} create?

• An empty set
• An empty dictionary
• An empty tuple
• A syntax error

Use set() for an empty set (lesson 23).

20. What happens with def add(item, basket=[])?

• A new list is created on each call
• The same list is shared between calls
• It's a syntax error
• The default is ignored

Defaults are evaluated once; use None instead (lesson 29).

21. Which keyword lets an inner function modify a variable of its enclosing function?

• global
• nonlocal
• outer
• static

nonlocal refers to the enclosing function's scope (lesson 30).

22. What does a function containing yield return when called?

• The first yielded value
• A list of values
• A generator object
• None

The body runs lazily as values are requested (lesson 35).

23. What does @functools.wraps(fn) do in a decorator?

• Caches the function's results
• Copies the original function's name and docstring onto the wrapper
• Makes the function async
• Prevents the function from being called

It keeps the decorated function's identity (lesson 34).

24. What is self in a method?

• The object the method was called on
• The class itself
• A reserved global
• The parent class

obj.method() passes obj as self (lesson 36).

25. Which special method controls how an object looks in lists and the shell?

• __str__
• __repr__
• __init__
• __print__

__repr__ is the developer-facing representation (lessons 36 and 38).

26. What does @dataclass generate automatically?

• A database table
• __init__, __repr__ and __eq__
• Getters and setters for every field
• Unit tests

Dataclasses remove boilerplate (lesson 40).

27. When does a finally block run?

• Only when there's no exception
• Only when there's an exception
• Always
• Only after a return

Use it for cleanup (lesson 41).

28. What does open("data.txt", "w") do if the file exists?

• Appends to it
• Erases its contents
• Raises an error
• Opens it read-only

"w" truncates; use "a" to append or "x" to refuse overwriting (lesson 43).

29. What is the purpose of a virtual environment?

• To run Python faster
• To keep each project's installed packages separate
• To make Python run in the browser
• To encrypt your code

One environment per project avoids version clashes (lesson 47).

30. Which module should you use to generate a secure password token?

• random
• math
• secrets
• hashlib only

random is predictable by design (lesson 48).