Python Coding challenge - Day 1268| What is the output of the following Python Code?

 

Code Explanation:

1️⃣ Creating Class A

class A:

This creates the base class A.

2️⃣ Defining f() in Class A

def f(self): return "A"

Class A has a method f() that simply returns:

"A"

So:

A().f()

produces:

A

3️⃣ Creating Class B

class B(A):

B inherits from A.

So B can use the methods of A, but B also defines its own version of f().

Inheritance:

B → A

4️⃣ Overriding f() in B

def f(self): return "B" + super().f()

Here B overrides A.f().

The expression has two parts:

"B" + super().f()

"B" contributes:

B

and:

super().f()

calls the next f() in the inheritance chain, which is:

A.f()

So:

super().f() → "A"

Therefore:

"B" + "A" → "BA"

5️⃣ Creating Class C

class C(B):

Now C inherits from B.

The inheritance chain becomes:

C → B → A

6️⃣ Overriding f() in C

def f(self): return "C" + super().f()

Again, C overrides f().

The first part is:

"C"

Then:

super().f()

from inside C moves to the next class in the MRO:

B

So:

super().f()

calls:

B.f()

7️⃣ Understanding the Nested Calls

When we execute:

C().f()

Python first enters:

C.f()

Inside C.f():

"C" + super().f()

calls B.f().

Then B.f() executes:

"B" + super().f()

which calls A.f().

Finally:

A.f() → "A"

So the calls work backward like this:

C.f()

 ↓

"C" + B.f()

          ↓

       "B" + A.f()

                ↓

               "A"

8️⃣ Combining the Results

Start from the deepest call:

A.f() → "A"

Then B.f():

"B" + "A"

→ "BA"

Then C.f():

"C" + "BA"

→ "CBA"

9️⃣ Printing the Result

print(C().f())

C().f() returns:

CBA

So the final output is:

CBA

🔄 Complete Execution Flow

C().f()

   ↓

C.f()

   ↓

"C" + B.f()

          ↓

       "B" + A.f()

                ↓

               "A"

          ↓

        "BA"

   ↓

"C" + "BA"

   ↓

"CBA"

🎯 Final Output

CBA

Book: 200 Days Python Coding Challenges with Explanation