Class definition syntax in Python - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of a simple class attribute access

What is the output of this Python code?

Python

class Dog:
    sound = "bark"

print(Dog.sound)

A bark

B Sound

C dog

D None

💡 Hint

Look at how class attributes are accessed directly from the class.

The class Dog has a class attribute 'sound' set to 'bark'. Accessing Dog.sound prints 'bark'.

❓ Predict Output

intermediate

Output of instance method call

What is the output of this Python code?

Python

class Cat:
    def meow(self):
        return "meow"

c = Cat()
print(c.meow())

A meow

B Meow

C None

D TypeError

💡 Hint

Instance methods need to be called on an object instance.

The method meow returns the string 'meow'. Calling c.meow() prints 'meow'.

❓ Predict Output

advanced

Output when __init__ is missing

What happens when you run this code?

Python

class Bird:
    def fly(self):
        return "flying"

b = Bird()
print(b.fly())

A None

B TypeError: missing 1 required positional argument

C AttributeError: 'Bird' object has no attribute 'fly'

D flying

💡 Hint

If __init__ is missing, Python uses a default constructor.

Python provides a default __init__ if none is defined, so b = Bird() works and b.fly() returns 'flying'.

❓ Predict Output

advanced

Output of class with instance variable

What is the output of this code?

Python

class Fish:
    def __init__(self, name):
        self.name = name

f = Fish("Nemo")
print(f.name)

A AttributeError

B Fish

C Nemo

D name

💡 Hint

Instance variables are set inside __init__ and accessed via self.

The instance variable 'name' is set to 'Nemo' during object creation and printed.

❓ Predict Output

expert

Output of class with method overriding and super()

What is the output of this code?

Python

class Animal:
    def speak(self):
        return "sound"

class Dog(Animal):
    def speak(self):
        return super().speak() + " bark"

d = Dog()
print(d.speak())

A bark

B sound bark

C sound

D TypeError

💡 Hint

super() calls the parent class method inside the child method.

Dog's speak calls Animal's speak via super(), returning 'sound', then adds ' bark'.