Python Comments

Creating a Comment

Comments can be used to explain Python code, make the code more readable, or prevent execution when testing code.

Comments start with a #, and Python will ignore them:

# This is a comment
print("Hello, World!")

Comments can be placed at the end of a line, and Python will ignore the rest of the line:

print("Hello, World!") # This is a comment

A comment does not have to be text that explains the code, it can also be used to prevent Python from executing code:

# print("Hello, World!")
print("Cheers, Mate!")

Multiline Comments

Python does not really have a syntax for multiline comments. To add a multiline comment you could insert a # for each line:

# This is a comment
# written in
# more than just one line
print("Hello, World!")

Or, not quite as intended, you can use a multiline string. Since Python will ignore string literals that are not assigned to a variable, you can add a multiline string (triple quotes) in your code, and place your comment inside it:

"""
This is a comment
written in
more than just one line
"""
print("Hello, World!")

As long as the string is not assigned to a variable, Python will read the code, but then ignore it, and you have made a multiline comment.

Best Practices for Comments

• Use comments to explain why something is done, not just what is done
• Keep comments concise and relevant
• Update comments when you change the code
• Use proper grammar and spelling in comments
• Avoid obvious comments that don't add value

# Calculate compound interest using the formula A = P(1 + r/n)^(nt)
amount = principal * (1 + rate/frequency) ** (frequency * time)

# Add 1 to x
x = x + 1