Python Quiz

Who created the Python programming language?

• Dennis Ritchie
• Guido van Rossum
• James Gosling
• Bjarne Stroustrup

Answer: Guido van Rossum. Guido van Rossum began Python in the late 1980s and released it in 1991. Ritchie created C, Gosling Java and Stroustrup C++.

Which keyword is used to define a function in Python?

• function
• func
• define
• def

Answer: def. Functions start with def, for example: def greet(name): followed by an indented body.

Which symbol starts a single-line comment in Python?

• # (hash)
• // (double slash)
• /* (slash star)
• -- (double hyphen)

Answer: # (hash). Everything after # on a line is ignored by Python. // is floor division in Python, not a comment.

How does Python mark which lines belong to a block, such as the body of a loop?

• Curly braces { }
• BEGIN and END keywords
• Indentation
• Semicolons

Answer: Indentation. Python uses indentation (usually four spaces) to group statements. Wrong indentation causes an IndentationError.

Which of these Python data types is immutable?

• list
• tuple
• dict
• set

Answer: tuple. A tuple cannot be changed after it is created. Lists, dictionaries and sets can be modified in place.

What is the output of print(7 // 2)?

• 3.5
• 4
• 3.0
• 3

Answer: 3. // is floor division: it divides and rounds down to a whole number, so 7 // 2 gives 3 (an int, since both operands are ints).

What is the output of print(10 / 2) in Python 3?

• 5.0
• 5
• 0.5
• Error

Answer: 5.0. In Python 3 the / operator always performs true division and returns a float, so 10 / 2 gives 5.0.

What does len("Hello") return?

• 4
• 6
• 5
• "Hello"

Answer: 5. len() counts the items in a sequence. "Hello" has five characters, so it returns 5.

What is the output of print("Hello"[::-1])?

• Hello
• olleH
• H
• o

Answer: olleH. The slice [::-1] steps through the string backwards, which reverses it: olleH.

Which block is used to catch and handle an error in Python?

• catch
• rescue
• on error
• except

Answer: except. Python uses try ... except. Code that might fail goes in try, and the except block runs if that error occurs.

What is the output of print(list(range(1, 10, 3)))?

• [1, 4, 7]
• [1, 4, 7, 10]
• [3, 6, 9]
• [1, 3, 6, 9]

Answer: [1, 4, 7]. range(start, stop, step) starts at 1, adds 3 each time and stops before 10, giving 1, 4 and 7.

a = [1, 2]; a.append([3, 4]). What is len(a) now?

• 2
• 4
• 3
• Error

Answer: 3. append() adds its argument as one item, so a becomes [1, 2, [3, 4]] with 3 items. extend() would have added 3 and 4 separately.

What is the output of print(bool("False"))?

• False
• True
• None
• Error

Answer: True. Any non-empty string is truthy, even the text "False". Only the empty string "" converts to False.

x = [1, 2, 3]; y = x; y.append(4). What does print(x) show?

• [1, 2, 3]
• [4]
• Error
• [1, 2, 3, 4]

Answer: [1, 2, 3, 4]. y = x does not copy the list; both names point to the same object, so changing y changes x too. Use x.copy() for a separate list.

What is the output of print(2 ** 3 ** 2)?

• 512
• 64
• 36
• 12

Answer: 512. The ** operator is right-associative, so Python works out 3 ** 2 = 9 first, then 2 ** 9 = 512.