Python Coding challenge - Day 1142| What is the output of the following Python Code?

 

Code Explanation:

🔹 1. Function Definition

def func(x, lst=[]):

✅ Explanation:

A function func is defined with:

x → number of iterations

lst=[] → default list

⚠️ Important:

This list is created only once (when function is defined, not called)

It is shared across all function calls

🔹 2. Loop Execution

for i in range(x):

✅ Explanation:

Loop runs from 0 to x-1

Adds numbers step by step

🔹 3. Appending Values

lst.append(i)

✅ Explanation:

Adds i into the same list lst

Since lst is shared → values accumulate over calls

🔹 4. Returning List

return lst

✅ Explanation:

Returns the updated list

🔹 5. First Function Call

print(func(3))

🔍 Execution:

x = 3

Loop runs: 0,1,2

List becomes:

[0, 1, 2]

✔️ Output:

[0, 1, 2]

🔹 6. Second Function Call

print(func(2))

🚨 Important:

Python does NOT create a new list

It uses the SAME previous list → [0,1,2]

🔍 Execution:

x = 2

Loop runs: 0,1

These values are appended to existing list:

[0,1,2] + [0,1] → [0,1,2,0,1]

✔️ Output:

[0, 1, 2, 0, 1]

🎯 Final Output

[0, 1, 2]

[0, 1, 2, 0, 1]

Book: 900 Days Python Coding Challenges with Explanation