Python Comments

Comments in Python are lines of text that are ignored by the Python interpreter during execution. They are used to explain code, make it more readable, and provide context for other developers who may read the code later.

Python comments serve as documentation within code and play a crucial role in making programs more understandable. They can describe the purpose of functions, clarify complex algorithms, or temporarily disable code during testing and debugging. Well-written comments contribute significantly to code maintenance and collaboration.

Syntax

Python offers three main ways to create comments:

• #: Single-line comment symbol that comments everything to its right on the same line
• Multiple #: Used on consecutive lines to create multi-line comments
• ''' or """: Triple quotes to create string literals that can function as multi-line comments when not assigned to variables

Note: Triple quotes (''' or """) create string literals, not true comments, though they’re often used like multi-line comments when unassigned.

Return value:

Python comments don’t return anything as they are completely ignored by the interpreter during execution.

Single-Line Comments

Single-line comments in Python start with the hash symbol (#). The Python interpreter ignores everything from the hash symbol to the end of the line.

Example 1: Basic Comment Example

This example demonstrates how to use single-line comments to document code:

# This is a single-line comment
print("Hello, World!")  # This is an inline comment

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The above code will result in:

Hello, World!

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Single-line comments can appear on their own line or at the end of a line of code. They’re useful for providing brief explanations or notes about specific lines of code.

Multi-line Comments

Python doesn’t have a specific syntax for multi-line comments like some other programming languages. However, developers commonly use multiple single-line comments to create multi-line comments.

Example 2: Using Multiple Single-Line Comments

This example shows how to create multi-line comments using consecutive single-line comments:

# This is a multi-line comment using
# multiple single-line comments.
# Each line starts with a hash symbol.
print("Multi-line comments in Python")

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This code generates the following output:

Multi-line comments in Python

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Using multiple single-line comments is the conventional way to create multi-line comments in Python. Each line needs to begin with the hash symbol.

String Literals as Comments

Python allows using triple-quoted strings (''' or """) as a way to create multi-line text. When these triple-quoted strings are not assigned to variables, they are ignored by the interpreter and can effectively function as comments.

Example 3: Using Triple Quotes as Comments

This example demonstrates using triple quotes to create multi-line comments:

"""
This is a multi-line comment using
triple quotes (string literals).
It can span multiple lines without
needing a hash symbol on each line.
"""
print("String literals as comments")

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This code produces an output as follows:

String literals as comments

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While this approach is sometimes used for multi-line comments, it’s important to note that these are technically string literals, not comments. They are most commonly used for docstrings to document functions, classes, and modules.

Codebyte Example: Combining Comment Types

Python developers often use different types of comments for different purposes. Here’s an example that demonstrates all three comment types in one program:

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This example shows how different comment types can be used together. Single-line comments for brief explanations, multiple single-line comments for longer explanations, and triple-quoted strings for function documentation.

Frequently Asked Questions

1. When should I use comments in my Python code?

Comments should be used to explain complex logic, clarify intentions, or provide context that isn’t obvious from the code itself. Good comments answer “why” rather than “what” (which should be clear from well-written code).

2. What’s the difference between comments and docstrings?

Comments (using #) are meant for code readers and are completely ignored by Python. Docstrings (using triple quotes) are special string literals that can be accessed programmatically through the __doc__ attribute. They’re used to document modules, classes, and functions.

3. Can comments affect my program’s performance?

No, comments don’t affect performance as they are completely removed during the compilation phase before execution. You can use as many comments as needed without worrying about performance impact.

4. What is /* */ in Python?

Unlike languages such as C, Java, or JavaScript, Python does not support the /* */ syntax for comments. This is a common source of confusion for programmers coming from other languages. In Python, you must use the # symbol for single-line comments or triple quotes (''' or """) for multi-line text blocks that function as comments.

5. How do I comment out multiple lines in Python?

There are three common approaches to comment out multiple lines in Python:

1. Add a # at the beginning of each line manually
2. Use your code editor’s block comment feature (usually a keyboard shortcut) to add # to selected lines
3. Enclose the code block in triple quotes (''' or """) to create a string literal that isn’t assigned to any variable