Python Coding challenge - Day 241 | What is the output of the following Python Code?

Code:

a = [1, 2, 3]

b = a

a.append(4)

print(b)

Solution and Explanantion: 

 a = [1, 2, 3]:

This line creates a list a with elements [1, 2, 3].

b = a:

Here, b is not a new list but a reference to the same list object that a refers to. In Python, variables that hold lists (and other mutable objects) actually hold references to the memory location where the list is stored. So, b now refers to the same list as a.

a.append(4):

This line adds the element 4 to the end of the list a. Since a and b refer to the same list, this modification affects both a and b.

print(b):

Since b refers to the same list as a, the output will show the modified list [1, 2, 3, 4].

Final Output:

[1, 2, 3, 4]

The key concept here is that a and b are references to the same list in memory, so changes to the list via one variable are reflected in the other.