What is a Multiline Comment in Python?

Why Use a Multiline Comment in Python Code?

The primary use of Python multiline comments is for documenting code. They allow programmers to add explanatory text or notes that provide information about the code's purpose, usage, or implementation details. These comments can be helpful for other developers who are working on the same codebase or for the programmer themselves when revisiting the code at a later time.

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How to Make Single Line Comments in Python?

In Python, single-line comments are created by prefixing the comment with the hash symbol (#). Anything following the hash symbol on the same line is considered a comment and is not executed as code. 

Read more about Comments in Python and Why Are the Important.

How to Make Multi-line Comments in Python?

To create multi-line comments in Python, you can use triple quotes (''' or """). Similar to multiline strings, these triple quotes can span multiple lines and enclose the comment text. Here's an example:

"""This is a multi-line comment.
It can span multiple lines.
These lines are not executed as code."""​

Types of Multiline Comments in Python

Consecutive Single-line Comments

You can create multiline comments by using multiple single-line comments consecutively. Each line begins with the hash symbol (#). Here's an example:

# This is a multiline comment
# that spans multiple lines
# in Python​

Using Multiline String as a Comment

Another way to create multiline comments in Python is by using triple quotes (either single or double quotes) to create a multiline string. Although the string is not technically a comment, it can be used as such because Python ignores it. Here's an example:

"""This is a multiline comment
that spans multiple lines
in Python"""​

Using Triple Quotes to Comment Out Multiple Lines

You can use triple quotes to create a multiline string that effectively comments out multiple lines of Python code. By enclosing the code within triple quotes, Python treats it as a string and ignores it during execution.

Ways to Use Different Shortcuts in IDE to Comment Out Multiple Lines

Different IDEs may have different shortcuts to comment out multiple lines of Python code. Here are the common shortcuts for some popular IDEs:

• Visual Studio Code: Use the shortcut Ctrl + / (Windows/Linux) or Command + / (Mac) to comment out selected lines or the current line. Use the same shortcut again to uncomment the lines.
• PyCharm: Use the shortcut Ctrl + / (Windows/Linux) or Command + / (Mac) to comment out selected lines or the current line. Use the same shortcut again to uncomment the lines.
• Sublime Text: Use the shortcut Ctrl + / (Windows/Linux) or Command + / (Mac) to toggle commenting for selected lines or the current line.

Way to Comment Out Multiple Lines in Visual Studio Code

To comment out multiple lines in Visual Studio Code, you can use the shortcut Ctrl + / (Windows/Linux) or Command + / (Mac). Select the lines you want to comment on, then press the shortcut to comment on them. Press the shortcut again to uncomment the lines.

Way to Comment Out Multiple Lines in PyCharm

To comment out multiple lines in PyCharm, follow these steps:

1. First, select the lines that you require to comment out.
2. Next, right-click on the selection and from the context menu, choose "Comment with Line Comment".
3. The selected lines will be commented out with a hash symbol (#) at the beginning of each line. Repeat the steps to uncomment the lines.

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How to Comment Out Multiple Lines in Sublime Text?

To comment out multiple lines in Sublime Text, follow these steps:

1. First, select the lines that you require to comment out.
2. Press Ctrl + / (Windows/Linux) or Command + / (Mac) to toggle commenting. The selected lines will be commented out with a hash symbol (#) at the beginning of each line.
3. Press the same shortcut again to uncomment the lines.

Docstrings in Python

Docstrings are used in Python to provide documentation for modules, functions, classes, and methods. They are enclosed in triple quotes and are used to describe the purpose, behavior, and usage of the code element they are attached to. Docstrings can be accessed at runtime using the built-in __doc__ attribute.

Read our article in which we discuss about the Python basics.

Difference Between Comments and Docstring in Python

The main difference between comments and docstring in Python is that comments are purely for human understanding and are ignored by the Python interpreter, while docstrings serve as documentation and can be accessed at runtime. Comments are often used for temporary notes, explanations, or to comment out lines of code, whereas docstrings are used to provide structured documentation for code elements.

Best Practices for Multiline Commenting in Python

Best Practices for Multiline Commenting in Python:

1. Use multiline comments sparingly: Multiline comments should be used only when necessary to provide additional context or explanation for complex code sections. Avoid excessive commenting for simple and self-explanatory code.
2. Keep comments concise and clear: Make sure your comments are clear, concise, and to the point. Use plain language and avoid unnecessary jargon or technical terms.
3. Use proper indentation and formatting: Maintain proper indentation and formatting in your multiline comments to enhance readability. Follow the PEP 8 style guide for consistency and clarity.
4. Keep comments up to date: Whenever you modify the code, make sure to update the corresponding comments if necessary. Outdated comments can be misleading and lead to confusion.
5. Use docstrings for documentation: For functions, classes, and modules, use docstrings instead of multiline comments. Docstrings provide structured documentation that can be accessed at runtime and through tools like Python's built-in help() function.
6. Consider code refactoring instead of commenting: If you find yourself needing extensive multiline comments to explain a code section, consider refactoring the code to make it more readable and self-explanatory. Clear and well-structured code is often better than extensive comments.
7. Review and remove unnecessary comments: Regularly review your codebase and remove any obsolete or unnecessary multiline comments. Keeping the code clean and clutter-free improves readability and maintainability.

Comment Out Multiple Lines in Python Using the Backslash Method

In Python, commenting out multiple lines can be useful for temporarily disabling parts of your code without deleting them. While Python does not have a direct syntax for multi-line comments like some other programming languages (e.g., /* */ in C/C++), there are several ways to achieve this, including using the backslash method.

Using the Backslash Method

The backslash (\) in Python is typically used as a line continuation character, allowing you to split a statement across multiple lines. However, when it comes to commenting out multiple lines, the backslash method can be creatively employed to achieve a similar effect. Here's how you can do it:

This is the first line of a multi-line comment \
# This is the second line of the same comment \
# This is the third line of the comment \
# And so on…

How It Works

Each line in the above example is treated as a separate comment because the hash (#) symbol is used at the beginning of each line. The backslash at the end of each line is not strictly necessary for commenting but is often used for line continuation in other contexts.

Using the backslash can make your intention clear, especially in long comments where you want to visually indicate that the lines are part of a continuous block. However, it's worth noting that this is not a conventional or widely recommended method for commenting out multiple lines in Python.

Alternative Methods

Triple Quoted Strings: A more common approach for multi-line comments is to use triple-quoted strings (''' or """). While these are technically multi-line strings, if not assigned to any variable, they effectively act as comments.

'''
This is a multi-line comment
using triple-quoted strings.
It spans multiple lines.
'''

Multiple Single-Line Comments: You can simply use the hash symbol (#) at the beginning of each line you want to comment out.

# This is a multi-line comment
# using multiple single-line comments.
# Each line is preceded by a hash symbol.

While the backslash method can be used to create a visually continuous block of comments, it is not the standard way to comment out multiple lines in Python. Most Python developers prefer using triple-quoted strings or multiple single-line comments for readability and clarity. Understanding these methods will help you choose the most appropriate way to document or temporarily disable sections of your code.

Conclusion

Multiline comments can be created in Python using consecutive single-line comments or by enclosing code within triple quotes. Triple quotes can also be used to comment out multiple lines of code. It's important to use multiline comments sparingly, keep them concise and clear, and maintain proper formatting. Docstrings are recommended for documenting code elements. Regularly reviewing and removing unnecessary comments improves code readability. Following these best practices enhances code understanding and maintainability.

If you are interested in enhancing your software development skills further, we would recommend you to check Simplilearn’s Python training course. This course can help you hone the right development skills related to Python and make you job-ready in no time.

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FAQs

1. What is the purpose of commenting out multiple lines in Python?

The purpose of commenting out multiple lines in Python is to temporarily disable or exclude a block of code from execution.

2. How do I comment out a single line of code in Python?

To comment out a single line of code in Python, you can simply prefix it with the hash symbol (#). 

3. What are the two ways to comment out multiple lines in Python?

There are two common ways to comment out multiple lines in Python:

1. Using consecutive single-line comments: Prefix each line with the hash symbol (#).
2. Using multiline strings as comments: Enclose the code within triple quotes (either single or double quotes). 

4. Can I use triple quotes to comment out a mixture of code and text in Python?

Yes, you can use triple quotes to comment out a mixture of code and text in Python. By enclosing the mixture within triple quotes, Python treats it as a multiline string and ignores it during execution.

5. How do I uncomment multiple lines in Python?

To uncomment multiple lines in Python, you simply need to remove the comment indicator (hash symbol, #) from the beginning of each line. Uncommenting allows the previously commented lines to be executed again.

6. Is it possible to nest comments in Python?

No, it is not possible to nest comments in Python. Once you start a comment with a hash symbol (#), anything after it on the same line is ignored. 

7. What is the difference between multiline string and multiline comment?

The difference between a multiline string and a multiline comment lies in their purpose and treatment by the Python interpreter. Multiline strings are enclosed within triple quotes and are treated as regular strings in Python, while multiline comments, created by consecutive single-line comments or multiline strings, are ignored by the interpreter and serve as documentation or temporary code exclusion.

8. Do comments affect the performance of my Python code?

Comments do not affect the performance of your Python code. The Python interpreter completely ignores comments during execution, so they have no impact on the runtime performance. Including comments in your code is considered good practice for readability and maintainability without any performance implications.

9. How to comment out multiple lines in python?

To comment out multiple lines in Python, you can use triple-quoted strings (''' or """) if not assigned to a variable, or use the hash (#) symbol at the beginning of each line. The backslash (\) method can also be used to indicate line continuation, though it's less common. Most developers prefer triple-quoted strings or multiple single-line comments for clarity.