append.md

Title	Description	Subjects	Tags	CatalogContent
.append()	Adds a single item to the end of a list in Python.	Code Foundations Computer Science	Arrays Data Structures Lists Methods	learn-python-3 paths/computer-science

The .append() method adds a single item to the end of an existing Python list. Lists in Python are mutable sequences that can store multiple items of different data types. When new elements need to be added to a list after it's been created, the .append() method provides a simple and efficient way to add items to the end of the list.

Syntax

list.append(item)

Parameters:

• item: An element of any data type (string, number, list, etc.) to be added to the end of the list.

Return value:

The method doesn't return any value (returns None). It modifies the original list in-place.

Example 1: Adding an item to a list

This example demonstrates how to add an item to the end of a list:

# Create a list of fruits
fruits = ['apple', 'banana', 'cherry']

# Add 'orange' to the list
fruits.append('orange')

# Print the updated list
print(fruits)

This example results in the following output:

['apple', 'banana', 'cherry', 'orange']

The original list fruits has been modified to include 'orange' as the last element. The .append() method added the new item directly to the end of the list.

Example 2: Adding list to a list

When appending a list to another list, the entire list is added as a single element:

# Create a list of fruits
fruits = ['apple', 'banana', 'cherry']

# Create a list of berries
berries = ['strawberry', 'blueberry']

# Append the berries list to the fruits list
fruits.append(berries)

# Print the updated list
print(fruits)

This example will generate the following output:

['apple', 'banana', 'cherry', ['strawberry', 'blueberry']]

Notice that the berries list has been added as a single item to the fruits list, creating a nested list structure. To add each element individually instead, the .extend() method would be more appropriate.

Codebyte example: Demonstrating .append() in Python

This example demonstrates how to use .append() to add various items including strings, numbers, and lists to a Python list:

# Create an empty shopping list
shopping_list = []

# Add items to the shopping list
shopping_list.append('bread')
shopping_list.append('milk')
shopping_list.append('eggs')

print("Shopping list:", shopping_list)

# Add a numeric item to the list
shopping_list.append(3)  # Number of apples

print("Updated shopping list:", shopping_list)

# Append a nested list
shopping_list.append(['cheese', 'butter'])

print("Final shopping list:", shopping_list)

# Access the nested list items
print("Dairy items:", shopping_list[4])

Frequently Asked Questions

1. What is .append() and .extend() in Python?

.append() adds a single item to the end of a list as one element, even if that item is itself a list. .extend() adds individual elements from an iterable (like another list) to the end of the current list. For example:

list1 = [1, 2, 3]
list1.append([4, 5])  # Results in [1, 2, 3, [4, 5]]
list2 = [1, 2, 3]
list2.extend([4, 5])  # Results in [1, 2, 3, 4, 5]

2. When can I use append?

You can use .append() whenever you need to add a single item to the end of an existing list. Common use cases include:

• Building a list dynamically as you collect data
• Adding user input to a list
• Accumulating results in a calculation
• Constructing a list step by step in algorithms

3. How to append a string?

Appending a string to a list works just like appending any other item. The string becomes a single element in the list:

words = ['hello', 'world']
words.append('python')  # Results in ['hello', 'world', 'python']

If you want to append each character of a string separately, you can use the .extend() method instead:

letters = ['a', 'b', 'c']
letters.extend('def')  # Results in ['a', 'b', 'c', 'd', 'e', 'f']