How to write multiline comments in Python

December 01, 2021

How to write a multiline comment in Python:

It is a good practice to comment code. It helps other developers to read and understand a new project. Comments are ignored by the compilers and they don’t make the code slow. In this post, I will show you how to write a multiline comment in Python and how to comment a line quickly in VSCode and PyCharm.

Single line comment:

You need to add a # before a line to mark it as a comment line.

# printing hello world
print('Hello World')

    # printing hello world again
print('hello world....')

I added two comment lines in this code snippet. It will not throw any IndentationError error.

But, it will be an error:

# printing hello world
print('Hello World')

    # printing hello world again
    print('hello world....')

    print('hello world....')
IndentationError: unexpected indent

Multiline comments:

For a multiline comment, you need to start and end it with """.

For example,

"""
This is a
multiline string
"""


def print_msg(msg):
    """
    :param msg: message to print
    :return: none
    """
    print(msg)


print_msg('Hello World')

Another way:

You can also use # before each line to comment out multiple lines:

# This is a
# multiline string

def print_msg(msg):
    # :param msg: message to print
    # :return: none
    
    print(msg)

print_msg('Hello World')

Comment out multiple lines in PyCharm or VSCode:

If you want to comment out multiple lines in IDE like PyCharm or VSCode, just select the lines and press Cmd + / on Mac or Cntrl + / on Windows or linux. It will comment out the lines.

By default, it will add a # before each of these lines, i.e. it will not use """.

Comments or docstring:

Make sure to do proper identation if you are using triple quotes. For example:

def print_msg(msg):
"""
:param msg: message to print
:return: none
"""
    print(msg)


print_msg('Hello World')

This will throw an IndentationError.

But if you use #, it will work:

def print_msg(msg):
# :param msg: message to print
# :return: none

    print(msg)


print_msg('Hello World')

It will work.

Because, if you use triple quotes, python interpreter doesn’t ignore those lines. If you use #, these lines are ignored.

Triple quotes are called docstrings and these are used to document a python module. So, if you want to comment multiple lines, not documentation, # is preferred.

N Kaushik