Python Coding challenge - Day 216 | What is the output of the following Python Code?

 

Code:

s = "hello"

t = s

s += " world"

print(s)

Solution and Explanation:

This code demonstrates the concept of mutable and immutable objects in Python, particularly focusing on strings.

Let's break it down step by step:

s = "hello": This line initializes a string variable s with the value "hello". Strings in Python are immutable, meaning once created, their contents cannot be changed.

t = s: This line creates another variable t and assigns it the same value as s. At this point, both s and t refer to the same string "hello".

s += " world": Here, a new string "hello world" is created by concatenating "hello" (the original value of s) with " world". However, since strings are immutable, this operation does not modify the existing string. Instead, it creates a new string and assigns it to s.

print(s): This line prints the value of s, which is now "hello world".

Now, let's see why t remains unchanged:

When t was assigned the value of s (t = s), it only received a reference to the original string "hello". Subsequent modifications to s do not affect t because t still refers to the original string "hello", which remains unchanged. Therefore, print(t) would output "hello".

This behavior occurs because strings are immutable in Python. If s were a mutable object, such as a list, modifying s would also affect t since they would both reference the same underlying object.