Comments & Best Practices0%
Variables Introduction and Rules

Comments & Best Practices

Beginner8 min read•Updated: 2026-09-03
Study Materials

Comments & Best Practices

Comments and docstrings document the intent behind code, making it readable and maintainable.

Key Concepts & Detailed Explanation

Good code documents itself, but great code explains 'why' non-obvious logic exists.

  • Single-line comments start with '#'.
  • Multi-line docstrings use triple quotes (''' or """) right beneath function/class definitions.
  • Follow PEP 8 guidelines: descriptive variable names, snake_case for functions, and 79-character line limits.

Code Examples & Output

Python
# Compute simple interest
def compute_interest(principal, rate_percent, years):
"""
Calculate simple interest.
Args:
principal (float): Amount invested
rate_percent (float): Annual interest rate
years (int): Number of years
Returns:
float: Total interest earned
"""
interest = (principal * rate_percent * years) / 100
return interest
 
print("Interest earned:", compute_interest(10000, 7.5, 3))

Expected Output:

Output
Interest earned: 2250.0

Best Practices & Common Pitfalls

Don't write comments that simply repeat the code (e.g. '# add 1 to x'). Explain the business reason.

Practice Quiz

1. Which syntax defines a docstring in Python?

  • A) // docstring
  • B) / docstring /
  • C) Triple quotes """ docstring """
  • D) <!-- docstring -->
Answer: C Explanation: Triple quotes are used for multi-line docstrings.

2. What naming convention does PEP 8 mandate for variables and functions?

  • A) camelCase
  • B) snake_case
  • C) kebab-case
  • D) PascalCase
Answer: B Explanation: PEP 8 prescribes snake_case (e.g. user_age, calculate_tax).

Practice Challenge

Write a function 'convert_celsius_to_fahrenheit' with a complete docstring and inline comments.

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