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Python Done Right
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Python Done Right · 100 lessons
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Syntax and definition
To define a function in Python, we use the def keyword followed by a function name, parentheses (), and a colon :. The indented block beneath forms the function body:
def function_name(parameters):
# Function body (indented)
return <value>
Writing this creates a function object associated with the name function_name - analogous to how x = 5 associates the integer 5 with x.
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Practice questions
4 questions
Which of the following correctly describes the role of the def keyword in Python?
Select the correct answer:
+ 3 more questions
Writing basic functions
Here is a function that calculates the area of a rectangle, returning 0 if either dimension is non-positive:
def calculate_rectangle_area(length, width):
area = 0
if length > 0 and width > 0:
area = length * width
return area
The function takes two parameters (length and width), validates that both are positive, then computes the area. If either is non-positive, area stays at 0.
We call the function by passing arguments in the parentheses. Because it has a return statement, we can capture the result:
my_area = calculate_rectangle_area(2, 4)
print(my_area) # Output: 8
print(calculate_rectangle_area(-2, 4)) # Output: 0
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Practice questions
4 questions
Recall the formula for the area of a circle:
In the Python Editor, define a function called circle_area which takes a single required parameter, radius and returns the area of the circle if r is positive, otherwise it returns 0.
Use the value of 3.14159 for .
Once you've written your function, run the code which sums the areas for several test circles. What is the total area to 2 decimal places?
Select the correct answer:
+ 3 more questions