Classes and Objects: What Does This Print

What does this print? · Advanced · about 10 min

Read each short program and type exactly what it prints, with each printed line on its own line. If a program stops with an error, type the error's name, like TypeError.

Example

class Cat:
    legs = 4
print(Cat().legs)

prints

Program 1

class Dog:
    def __init__(self, name):
        self.name = name
    def speak(self):
        return self.name + " says woof"
d = Dog("Rex")
print(d.speak())

What it prints

Program 2

class Counter:
    count = 0
a = Counter()
b = Counter()
a.count = 5
print(a.count, b.count, Counter.count)

What it prints

Program 3

class Bag:
    items = []
    def add(self, x):
        self.items.append(x)
a, b = Bag(), Bag()
a.add(1)
print(b.items)

What it prints

Program 4

class A:
    def hello(self):
        return "A"
class B(A):
    def hello(self):
        return "B+" + super().hello()
print(B().hello(), A().hello())

What it prints

Program 5

class Temp:
    def __init__(self, c):
        self.c = c
    def __str__(self):
        return f"{self.c} C"
    def __repr__(self):
        return f"Temp({self.c})"
print(Temp(20), [Temp(5)])

What it prints

Program 6

class Box:
    def size():
        return 3
print(Box().size())

What it prints

Program 7

class Square:
    side = 3
    @property
    def area(self):
        return self.side ** 2
s = Square()
s.side = 4
print(s.area)

What it prints

Program 8

class P:
    def __init__(self, v):
        self.v = v
a, b = P(1), P(1)
print(a == b, a.v == b.v)

What it prints