Python Coding challenge - Day 1099| What is the output of the following Python Code?

 

Code Explanation:

1️⃣ Defining the Class

class A:

Explanation

A class named A is created.

This class will store a list in each object.

2️⃣ Constructor with Default Argument

def __init__(self, lst=[]):

Explanation ⚠️ (VERY IMPORTANT)

lst=[] is a default argument.

This list is created only once when the function is defined.

It is shared across all objects if no argument is passed.

3️⃣ Assigning List to Object

self.lst = lst

Explanation

Assigns the list to the object.

But since default list is shared → all objects point to same list.

4️⃣ Creating First Object

a1 = A()

Explanation

No argument passed → uses default list [].

Now:

a1.lst → []

5️⃣ Modifying List via First Object

a1.lst.append(1)

Explanation

Adds 1 to the list.

Since list is shared:

lst → [1]

6️⃣ Creating Second Object

a2 = A()

Explanation

Again no argument → uses SAME default list.

So:

a2.lst → [1]

7️⃣ Modifying List via Second Object

a2.lst.append(2)

Explanation

Adds 2 to the SAME shared list.

Now:

lst → [1, 2]

8️⃣ Printing the Result

print(a1.lst, a2.lst)

Explanation

Both objects refer to the same list.

📤 Final Output

[1, 2] [1, 2]

Book: 400 Days Python Coding Challenges with Explanation