Python List In-Place Modification Example

Consider the following code in Python: def add_item(lst): lst.append(100) a = [1, 2, 3] add_item(a) print(a) What happens here? The correct explanation is: ✅ An in-place modification occurs on the list. Lists in Python are mutable objects, which means they can be modified after they are created. Let’s break it down step by step. 1️⃣ Creating the list When we write: a = [1, 2, 3] Python creates a list object in memory, and the variable a references it: a → [1, 2, 3] 2️⃣ Calling the function When the function is called: add_item(a) The parameter lst inside the function now references the same list object: a → [1, 2, 3] lst → ↑ (same list) ➡️ Both variables point to the same object in memory. 3️⃣ Inside the function Inside the function we execute: lst.append(100) The append() method modifies the list itself. This is called in-place modification, meaning the original list object is updated instead of creating a new one. The list now becomes: [1, 2, 3, 100] 4️⃣ Printing the result Since both a and lst reference the same list, the change is visible through a. Now when we execute: print(a) Output: [1, 2, 3, 100] 📌 Final thought Understanding how variables reference objects in memory is essential when working with mutable data types like lists in Python. #Python #PythonProgramming #Coding #LearnPython #SoftwareDevelopment

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