Parent and child classes in Python - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of method overriding in child class

What is the output of this code when calling child.greet()?

Python

class Parent:
    def greet(self):
        return "Hello from Parent"

class Child(Parent):
    def greet(self):
        return "Hello from Child"

child = Child()
print(child.greet())

A Hello from Parent

B Hello from Child

C None

D AttributeError

💡 Hint

Child class method with the same name replaces the parent's method.

The child class overrides the greet method, so calling greet on a Child instance runs the Child's version.

❓ Predict Output

intermediate

Accessing parent method from child

What is the output of this code?

Python

class Parent:
    def greet(self):
        return "Hello from Parent"

class Child(Parent):
    def greet(self):
        parent_greet = super().greet()
        return parent_greet + " and Child"

child = Child()
print(child.greet())

A Hello from Parent and Child

B Hello from Parent

C Hello from Child

D TypeError

💡 Hint

super() calls the parent class method.

The child calls the parent's greet method using super(), then adds its own text.

❓ Predict Output

advanced

Instance variable shadowing in child class

What is the output of this code?

Python

class Parent:
    def __init__(self):
        self.value = 10

class Child(Parent):
    def __init__(self):
        self.value = 20

obj = Child()
print(obj.value)

A AttributeError

B 10

C 20

D None

💡 Hint

Child's __init__ replaces Parent's __init__ unless explicitly called.

Child's __init__ sets value to 20 and does not call Parent's __init__, so value is 20.

❓ Predict Output

advanced

Calling parent constructor in child class

What is the output of this code?

Python

class Parent:
    def __init__(self):
        self.value = 10

class Child(Parent):
    def __init__(self):
        super().__init__()
        self.value = 20

obj = Child()
print(obj.value)

A 20

B 10

C AttributeError

D TypeError

💡 Hint

super().__init__() runs the parent's constructor first.

Parent's __init__ sets value to 10, then Child sets it to 20, so final value is 20.

❓ Predict Output

expert

Multiple inheritance method resolution order (MRO)

What is the output of this code?

Python

class A:
    def greet(self):
        return "Hello from A"

class B(A):
    def greet(self):
        return "Hello from B"

class C(A):
    def greet(self):
        return "Hello from C"

class D(B, C):
    pass

d = D()
print(d.greet())

A Hello from A

B TypeError

C Hello from C

D Hello from B

💡 Hint

Python uses the method resolution order (MRO) to decide which method to call.

Class D inherits from B and C. B is checked first in MRO, so B's greet is called.