Python Coding challenge - Day 1049| What is the output of the following Python Code?

 

Code Explanation:

🔹 1. Defining Class A

class A:

    x = "A"

Creates a base class A

Defines a class variable x with value "A"

Any subclass can inherit this variable

🔹 2. Defining Class B (Inherits from A)

class B(A):

    pass

B inherits from A

No x is defined in B

So B inherits A.x

📌 At this point:

B.x → "A"

🔹 3. Defining Class C (Overrides x)

class C(A):

    x = "C"

C inherits from A

Defines its own class variable x

This overrides A.x inside C

📌 Now:

C.x → "C"

🔹 4. Defining Class D (Multiple Inheritance)

class D(B, C):

    pass

D inherits from both B and C

No x is defined in D

Python must decide which parent’s x to use

➡️ This is where MRO (Method Resolution Order) comes into play.

🔹 5. Understanding MRO of Class D

Python calculates MRO using the C3 linearization algorithm.

D.mro()

Result:

[D, B, C, A, object]

📌 This means Python looks for attributes in this order:

D

B

C

A

object

🔹 6. Attribute Lookup for D.x

print(D.x)

Step-by-step lookup:

D → ❌ no x

B → ❌ no x (inherits but doesn’t define)

C → ✅ x = "C" found

Stop searching

✅ Final Output

C

700 Days Python Coding Challenges with Explanation