Comments
Comments explain code and are ignored when the program runs.
Syntax
# this is a commentComments are notes in your code that Python ignores. Use them to explain what your code does.
Writing comments
- Anything after a
#on a line is a comment. - Python has no dedicated multi-line comment, so you put a
#on each line. - A triple-quoted string is often used as a block note or docstring.
Example
# This is a single-line comment
x = 10 # set x to 10
# Each line of a
# multi-line note starts with a hash
print(x)
# Output:
# 10When to use it
- A developer adds inline comments to explain a complex formula so future maintainers understand it.
- A learner comments out a print statement temporarily while debugging an error.
- A team uses docstrings at the top of every function to auto-generate API documentation.
More examples
Inline and block comments
Shows a block comment above code and an inline comment after an expression.
# Calculate the area of a circle
radius = 5 # in centimetres
PI = 3.14159
area = PI * radius ** 2
print(area) # 78.53975Comment out code for debugging
Demonstrates using a comment to temporarily disable a line without deleting it.
x = 10
# x = 20 # disabled during debugging
print(x)
# Output:
# 10Docstring as function note
Uses a triple-quoted docstring to document a function's purpose, readable by help().
def greet(name):
"""Return a personalised greeting string."""
return f'Hello, {name}!'
print(greet('Ada'))
# Output:
# Hello, Ada!
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