Comments

301.7 Maintainable Code

Maintainable Code — Note 3 of 4

Explain code blocks.

What you need to know

Comments are notes in the code that Python ignores. Use # for single-line comments. Good comments explain why code does something, not what it does (the code itself shows that).

What to know

# starts a single-line comment
Comments are ignored by Python
Explain WHY, not WHAT: # Apply 20% discount
Don't over-comment obvious code
Use comments to mark sections of a program

Code examples

Using comments

python

# Calculate final price with VAT
price = 50
vat = price * 0.2  # 20% VAT rate
total = price + vat
print(total)

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Specification notes for programming are in Paper 2.