Multiline Comments in Python

Writing code with good readability is as important as writing functional code. In Python, comments are an important aspect of code that is responsible for clarifying complex logic, documenting changes, and disabling code temporarily during debugging. Comments play a vital role in explaining your logic, clarifying tricky sections, or disabling chunks of code during debugging. Unlike some programming languages, Python does not have a built-in syntax for multiline comments. However, there are several effective ways to write multiline comments in Python. This blog covers methods, styles, and best practices for writing clear multiline comments, along with common mistakes to avoid.

Table of Contents:

• What are Multiline Comments in Python?
• What Makes Multiline Comments Useful in Python?
• Multiline Comments: Types and Examples in Python
  • 1. Using # in Python
  • 2. Using Triple-Quoted Strings in Python
  • 3. Using Docstrings in Python
• Comparison Table: Methods to Write Multiline Comments in Python
• Commenting Multiple Lines Using Keyboard Shortcuts in Python IDEs
• Do Comments Affect Your Python Program’s Speed or Behaviour?
• Common Mistakes to Avoid While Implementing Multiline Comments in Python
• Best Practices for Writing Effective Comments in Python
• Conclusion

What are Multiline Comments in Python?

There are situations where single-line comments are not effective. Here, multiline comments are used to offer more flexibility. Comments help keep your code easy to understand, even long after you write it. Without comments, even good code can be hard to follow for others or for yourself later. Python provides various methods to implement multiline comments. This will make it easier to document large code sections or logic blocks.

What Makes Multiline Comments Useful in Python?

Multiline comments are ideal for explaining complex logic, clarifying configuration sections, or providing context for design decisions. They are particularly valuable in team projects or when working on extensive scripts. These comments help keep the code clean and easy to manage, especially when working with others or on big projects. They let you quickly disable parts of your code during debugging without deleting them.

Before exploring multiline comments, it’s important to understand single-line comments in Python using the symbol #. Single-line comments are the simplest and most frequently used form. They begin with a hash symbol and extend to the end of the line. These are best suited for brief explanations or notes about the code that follows.

Example: Single-Line Comment

Output:

Explanation: Here, the # symbol tells Python to ignore everything to its right. You can use it at the start of a line or next to a line of code to explain what that line does.

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Multiline Comments: Types and Examples in Python

Python lacks a dedicated multiline comment syntax like /* … */ in C or Java, but there are several effective ways. Learning these alternatives allows for flexible commenting based on context and code structure. Each approach serves a specific purpose, and selecting the right one enhances code clarity and maintainability.

Python offers three effective ways to create multiline comments:

1. Using # in Python: Stack # at the beginning of each line.
2. Triple-Quoted Strings: Use ”’ or “”” for block comments that aren’t assigned to variables.
3. Docstrings: Used within functions, classes, or modules for documentation purposes.

Let us proceed with explaining these types in detail with examples:

1. Using # in Python

This is the most common way to write multiline comments in Python. You simply prefix each line with a # symbol.

Example:

Output:

Explanation: Here, each line beginning with # is ignored by the Python interpreter. This method is clear, readable, and supported by all IDEs and linters. Linters are static code analysis tools that analyze code without executing it, providing feedback on potential errors, stylistic issues, and deviations.

2. Using Triple-Quoted Strings in Python

Python allows strings enclosed in triple quotes (”’ or “””) to span multiple lines. If you place these strings in your code without assigning them to any variable or function, they are ignored during execution. Keep in mind that if they’re not assigned to a variable or used as a docstring, they are still treated by the interpreter as strings. This means they aren’t ignored like comments and can cause unintended effects if used incorrectly.

Example:

Output:

Explanation: Here, the triple-quoted text is an unassigned string that Python ignores during execution. It works like a multiline comment but may cause warnings in some code checkers.

Note: This string is not a comment. It is compiled and stored in memory, unlike real comments using #, which are completely ignored.

3. Using Docstrings in Python

Docstrings are specific string literals that occur as the first statement in a module, function, class, or method definition. They are used for documentation purposes and can be accessed via the __doc__ attribute or the help() function. Using docstrings outside of these contexts is not standard practice and may lead to confusion.

Example:

Output:

Explanation: Here, docstrings are acting as documentation and can serve the purpose of a structured multiline comment, especially for documenting code blocks.

Note: Avoid using docstrings as generic multiline comments. They are meant for documentation and are stored in memory, making them unsuitable for general commenting purposes.

Comparison Table: Methods to Write Multiline Comments in Python

Commenting Multiple Lines Using Keyboard Shortcuts in Python IDEs

Modern IDEs simplify commenting multiple lines with keyboard shortcuts. This improves efficiency and minimises repetitive typing. Knowing these shortcuts helps quickly enable or disable sections of code while debugging, making the process faster and smoother. Although shortcuts differ by IDE, they usually follow similar patterns.

• VS Code: Ctrl + / (Windows/Linux), Cmd + / (macOS)
• PyCharm: Ctrl + / or Ctrl + Shift + / (Windows/Linux), Cmd + / or Cmd + Shift + / (macOS)

Try an example like this: 

Explanation: Here, using a shortcut, you can toggle comments for multiple lines quickly without manually adding # for each.

Do Comments Affect Your Python Program’s Speed or Behaviour?

Comments have no impact on runtime performance or program behaviour. The Python interpreter skips all comments during execution. No matter how many comments you write, Python removes them before running the code, so they don’t slow down your program. This means you can add comments freely for clarity without affecting application speed.

Let us execute a program without comments and see the execution time.

Example:

Output:

Explanation: Here, the execution time measures how long the code runs without comments

Now, let us execute a program with comments and see the execution time.

Example:

Output:

Explanation: Here, the execution time measures how long the code runs with comments, showing that comments do not affect performance.

Common Mistakes to Avoid While Implementing Multiline Comments in Python

1. Using comments for obvious code: Don’t write comments like # increment i next to i += 1.
2. Outdated comments: Always update comments when the code changes.
3. Using triple quotes for comments inside functions: These can be confused with docstrings.
4. Over-commenting: Too many comments can make the code hard to read.
5. Ignoring code formatting: Make sure multiline comments are properly indented for readability.
6. Writing vague comments: Comments should be clear and specific to add real value.

Best Practices for Writing Effective Comments in Python

While comments enhance code clarity, poor commenting habits can create confusion. Here are some tips:

1. Plan your comments to keep the code clean and easy to maintain.
2. Explain important logic, assumptions, or tricky parts.
3. Avoid commenting every single line and only add comments wherever necessary.
4. Keep comments short and clear.
5. Use the same style and format throughout your project for consistency.

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Conclusion

Python uses simple and flexible ways to write multiline comments without a special syntax like other programming languages. You can use different methods, like adding many single-line comments with # or using triple-quoted strings (docstrings) to make your code easier to read and maintain. Comments help connect people’s understanding with the code’s logic. They also make fixing problems and working with others easier by clearly explaining the logic of the code. Good comments make your code clean, reliable, and easy to understand and use.

Further, check out our Python Certification course and get ready to excel in your career with our Basic Python Interview Questions prepared by experts.

Multiline Comments in Python-FAQs