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Comments in Python

Alstergymnasium Python
🧠 Here’s a complete cheat sheet on comments, documentation, and code style in Python – ideal for beginners, students, and advanced users. It shows how to use comments correctly, how to document code, and how to write readable, clean Python code.

📝 Python Cheat Sheet – Comments, Documentation & Style
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💬 Comments in Python
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🔹 Single-line Comments
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Use # to comment a line:

# This is a comment
name = "Lena"  # Comment at the end of a line

✅ Ignored by the interpreter
✅ Use them for explanations, notes, or TODOs

🔹 Multi-line Comments (informal)
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Multiple # lines in a row:

# This is a multi-line comment
# It explains what the following code does
# and why it's important.

🔹 Docstrings (official documentation)
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Use triple quotes """ or ''' for documentation of functions, classes, and modules:

def greeting(name):
    """Returns a greeting for the given name."""
    return f"Hello, {name}!"

✅ Docstrings are readable with help()
✅ Used as official description

📚 Docstrings for Classes & Methods
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class Student:
    """Represents a student with name and age."""

    def __init__(self, name, age):
        """Initializes the student with name and age."""
        self.name = name
        self.age = age

🧠 Best Practices for Comments
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✅ Explain the “why”, not just the “what”
✅ Keep comments current – outdated comments are confusing
✅ Avoid obvious comments:

x = x + 1  # Increments x by 1  ❌ (too obvious)

✅ Use comments for complex logic, exceptions, or important notes

🎨 Code Style according to PEP 8
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Style Rule Example
Indentation: 4 spaces def func(): → ␣␣␣␣print()
Empty line between functions Separate functions with empty lines
Max. 79 characters per line Break long lines
snake_case for variables user_name = "Lena"
PascalCase for classes class Student:
Spaces around operators x = a + b
No spaces before parentheses print("Hello")

🧪 TODOs & Notes
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# TODO: Extend function for multiple names
# FIXME: Fix error with number input
# NOTE: This function will be replaced later

✅ Practical for teamwork and personal reminders

🔍 Comments vs. Docstrings
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Type Purpose Syntax Visible with help()
Comment Note for developers # Comment ❌ No
Docstring Documentation for users """Text""" ✅ Yes

🧠 Memory Tip for Students:
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💬 Comments help you think.
📚 Docstrings help others understand.