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How to Comment Out Multiple Lines in Python?

🔥 published June 15, 2023 - updated January 31, 2024

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Logan Romford by Logan Romford
6 min read 0 comments

Python is a versatile programming language that offers a variety of methods for commenting out code, enhancing both readability and debugging processes. The two primary methods for commenting out multiple lines in Python are the use of the hash character (#) and the creation of multi-line strings or docstrings. Additionally, there are various keyboard shortcuts available in different text editors to speed up the process. Let’s get to know this topic, so it will be easier to do my Python homework in the future.

Python Multiline Comment

Python does not have a specific syntax for multiline comments like some other programming languages, such as JavaScript or Java. However, there are several effective workarounds to achieve the same effect. One popular method involves using docstrings, which are typically used for programming documentation and code summaries.

To create a docstring, place triple double-quotes (""") or triple single-quotes (''') before and after the block of code you wish to comment out. This turns the lines into a multi-line string. When a string isn’t assigned to a variable, Python will ignore it when running the code. This method effectively comments out the desired code block, but Python’s style guide recommends using the hash character (#) for multi-line block comments​.

# This is a multi-line comment
# in Python
print("Hello, World!")

Alternatively, you can use triple quotes (''' or """) to comment out multiple lines. This method is technically not a comment but a docstring (short for documentation string). Python will ignore these lines as long as they’re not assigned to a variable:

"""
This is a multi-line comment
in Python
"""
print("Hello, World!")

In the code snippet above, Python will ignore the lines enclosed within the triple quotes and only run the print function. Docstrings are typically used for providing documentation for Python functions, methods, and classes, but they can be used as a workaround for multi-line comments.

Single Line Comments and Multi-line Comments

The use of the hash character (#) is the traditional way of creating single-line comments in Python. By placing a # and a space before each line, you can effectively comment out individual lines of code. This method is also applicable to multiple lines if you prepend the hash character to each line you want to comment out​​.

The distinction between single line comments and multi-line comments in Python revolves around how the hash character and docstrings are employed. For single line comments, the # symbol is used at the beginning of the line. For multi-line comments, each line could be prepended with a #, or a docstring can be used, which is a workaround in the absence of a specific multi-line comment syntax in Python.

# This is a single line comment in Python
print("Hello, World!")

In the code snippet above, Python will ignore the first line starting with #, and it will only run the print function.

The Importance of Commenting

Commenting is a crucial aspect of writing readable code. It allows other team members to understand your code and makes the debugging process easier. Comments are effectively notes to yourself and other developers. They can explain the purpose of a section of code, make a note of something that needs to be fixed in the future, or even be used to temporarily disable a piece of code during testing.

Commenting out code is a common practice during the debugging process. By commenting out a section of code, you can isolate problems by process of elimination. In Python, both single line comments and multi-line comments can be used to disable a piece of code temporarily.

Commenting and Debugging

Commenting out lines of code is an essential part of debugging. It allows you to isolate sections of your code to identify errors or unexpected behavior. By commenting out lines or blocks of code, you can run parts of your code separately to see if they function as expected.

Python Commenting in Different Text Editors

Different text editors have keyboard shortcuts for commenting out multiple lines in Python. For instance, in Notepad++, you can use Ctrl + Q to comment out selected lines of code. In PyCharm, the shortcut is Ctrl + /.

Remember, the key to good commenting is to ensure it enhances the readability of your code. It should provide clear and concise explanations of what your code does, making it easier for others (and for you) to understand, debug, and maintain.

Python comment shortcut keys

  • PyCharm:
    • Comment: Ctrl + / (Windows/Linux), Cmd + / (Mac)
    • Uncomment: same as the comment, it’s a toggle.
    • Block Comment: Ctrl + Shift + / (Windows/Linux), Cmd + Shift + / (Mac)
  • Visual Studio Code:
    • Comment: Ctrl + / (Windows/Linux), Cmd + / (Mac)
    • Uncomment: same as the comment, it’s a toggle.
    • Block Comment: Shift + Alt + A (Windows/Linux), Shift + Option + A (Mac)
  • Sublime Text:
    • Comment: Ctrl + / (Windows/Linux), Cmd + / (Mac)
    • Uncomment: same as the comment, it’s a toggle.
    • Block Comment: Ctrl + Shift + / (Windows/Linux), Cmd + Shift + / (Mac)
  • Jupyter Notebook:
    • Comment: Ctrl + / (Windows/Linux), Cmd + / (Mac)
    • Uncomment: same as the comment, it’s a toggle.
  • Atom:
    • Comment: Ctrl + / (Windows/Linux), Cmd + / (Mac)
    • Uncomment: same as the comment, it’s a toggle.
    • Block Comment: Ctrl + Shift + / (Windows/Linux), Cmd + Shift + / (Mac)
  • Thonny:
    • Comment: Ctrl + 3 (Windows/Linux), Cmd + 3 (Mac)
    • Uncomment: Ctrl + 4 (Windows/Linux), Cmd + 4 (Mac)

Conclusion

Understanding how to comment out multiple lines of code effectively is a fundamental skill in Python programming. While Python doesn’t have a specific syntax for multi-line comments like some other programming languages, the use of the hash character and docstrings provides efficient workarounds.

Regardless of the method you choose, it’s essential to comment your code consistently and clearly. Not only does it make your code more readable to others, but it also makes your life easier when you come back to a piece of code after a long period. Remember, good commenting practices contribute to better code, and better code leads to successful programming.

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FAQ

How do I comment out multiple lines of code in Python?

To comment out multiple lines of code in Python, you can place a # symbol at the beginning of each line you want to comment out. Some code editors and IDEs provide shortcuts to comment out multiple lines at once. For example, in PyCharm you can select the lines you want to comment and press Ctrl + Shift + / (Windows/Linux) or Cmd + Shift + / (Mac).

What is the syntax for commenting out multiple lines in Python?

The syntax for commenting out multiple lines in Python is to place a # symbol at the beginning of each line. Python does not have a specific syntax for block comments, unlike some other programming languages.

Can I comment out blocks of code in Python?

Yes, you can comment out blocks of code in Python by placing a # symbol at the beginning of each line in the block. Some IDEs and text editors provide shortcuts for doing this quickly. Additionally, you can use triple-quoted strings as a workaround for block comments, but this is technically creating a string and not a comment.

Does commenting out code affect the performance of my Python program?

No, commenting out code does not affect the performance of your Python program. Comments are ignored by the Python interpreter, so they have no impact on the execution of the code.

Are comments ignored by Python compilers and interpreters?

Yes, comments are ignored by Python compilers and interpreters. They are intended for human readers and do not have any effect on the execution of the code.

What is the difference between single-line comments and multi-line comments in Python?

In Python, single-line comments begin with a # symbol and only apply to a single line. Multi-line comments do not have a special syntax in Python, so you typically use the # symbol at the beginning of each line. Alternatively, you can use triple-quoted strings to comment out blocks of text, but this is technically creating a string and not a comment.

Can I use docstrings as a workaround for multi-line comments in Python?

Yes, you can use docstrings (triple-quoted strings) as a workaround for multi-line comments in Python. Although they are technically strings and not comments, they can be used to provide multi-line explanations or documentation within code. However, it’s important to note that unlike comments, docstrings are not completely ignored by the interpreter and can be accessed programmatically.

How do I handle indentation when using docstrings for commenting?

When using docstrings for commenting, you should align the triple-quoted strings with the block of code they are associated with, to maintain readability. As with regular code, it is important to be consistent with indentation to make the code structure clear.

Should I use regular Python comments or docstrings for multi-line comments?

Regular Python comments with # are typically used for short explanations and notes. Docstrings are usually used for providing documentation for modules, classes, and functions. If you are writing a brief comment, even if it spans multiple lines, the # symbol is preferable. If you are providing detailed documentation that should be accessible programmatically, use docstrings.

Can I prevent specific lines of code from running by commenting them out?

Yes, you can prevent specific lines of code from running by commenting them out. By placing a # symbol at the beginning of a line, that line is ignored by the Python interpreter and will not be executed. This is commonly used for temporarily removing code during debugging or development.

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