How do I create multiline comments in Python? – Programming Guide

In Python programming, writing clear and concise comments is essential for maintaining readable and maintainable code. Multiline comments play a crucial role when you want to explain a block of code, outline a complex logic, or provide detailed notes.

What Are Multiline Comments in Python?

Multiline comments are comments spanning multiple lines that help explain or clarify sections of code. Unlike single-line comments, which use the # symbol for each line, multiline comments allow grouping commentary in a more readable format.

How to Create Multiline Comments in Python

Method 1: Using Consecutive Single-Line Comments

The simplest and most common approach to multiline comments in Python is using # at the beginning of each line:

# This is a multiline comment
# in Python using single-line
# comment symbols consecutively.

This method is straightforward and highly readable for developers, but it can be visually lengthy if you have many lines.

Method 2: Using Multiline Strings (Triple Quotes)

Python does not have a dedicated multiline comment syntax like some other languages, but multiline string literals — strings enclosed within triple quotes (''' ... ''' or """ ... """) — can be used as multiline comments.

'''
This is a multiline comment
using triple single quotes.
It can also span across many lines.
'''

"""
Similarly, this uses triple double quotes
for multiline comments in Python.
"""

Technically, these are string literals and not comments, so if placed outside of assignments or expressions, they are ignored by the interpreter. Hence, they serve well as multiline comments.

Important Note

Using triple-quoted strings as comments only works when these strings are not assigned or used; otherwise, they’re treated as string objects. For actual commenting, the # symbol is preferred.

Examples of Multiline Comments in Python

Example 1: Commenting a Function Explanation

def calculate_area(radius):
    # Calculate the area of a circle
    # using the formula: area = π * r^2
    pi = 3.14159
    area = pi * radius ** 2
    return area

Example 2: Using Triple Quotes as Comments

def greet(name):
    """
    This function greets the person
    with the given name.
    """
    print(f"Hello, {name}!")

Here, the triple quotes form a docstring which also serves as a multiline comment explaining the function.

Example 3: Using Triple Quotes for General Comments

'''
This script performs data processing
on monthly sales data and outputs
the analysis results.
'''
print("Running sales data analysis...")

Interactive Example

Try this simple interactive Python snippet to see multiline comments in action:

def interactive_demo():
    # This demo shows usage of multiline comments
    print("Start of demo")
    
    '''
    The following code block calculates sum and product
    of two numbers and demonstrates multiline comment usage.
    '''
    
    a = 5
    b = 3
    sum_ab = a + b  # Sum calculation
    product_ab = a * b  # Product calculation
    
    print("Sum:", sum_ab)
    print("Product:", product_ab)
    
interactive_demo()

Best Practices for Multiline Comments in Python

• Use # for commenting multiple lines for clarity and tool compatibility.
• Reserve triple-quoted strings primarily for docstrings that explain modules, classes, or functions.
• Keep comments clear, concise, and relevant to avoid cluttering the code.
• Use comments to explain the “why” behind code, not just the “what”.
• Avoid excessive commenting that repeats obvious code.

Summary

Multiline comments in Python can be created by writing consecutive single-line comments starting with # or by using triple-quoted strings when not assigned to a variable. While Python lacks a distinct multiline comment syntax, these methods help keep code well-documented and understandable. Docstrings, which use triple quotes, are a Pythonic way to describe functions and classes and also act as readable multiline comments.

Good commenting practices improve code maintainability and assist teams and future developers to understand the logic effortlessly.