How To Avoid Returning None In Python

Python is a powerful programming language that is used by developers worldwide. However, returning None is not an uncommon practice in Python.

When Python code is executed, functions may return None instead of a value. This is often a source of frustration for developers. But don’t worry! In this tutorial, you will learn how to avoid returning None in Python.

Steps to Avoid Returning None in Python

Let’s take a look at some steps you can follow to avoid returning None in Python.

StepDescription
1Always have a return statement in your function
2Return a meaningful value instead of None
3Use assertion statements to check the return value of a function

Step 1: Always have a return statement in your function

In Python, if a function does not have a return statement, it will automatically return None.

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def add_numbers(a, b):
    result = a + b

Here, if you call the add_numbers function, it will return None.

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add_numbers(2, 3)

output:

None

To avoid returning None, make sure that your function always has a return statement.

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def add_numbers(a, b):
    result = a + b
    return result

Now, if you call the add_numbers function, it will return the sum of the two numbers instead of None.

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add_numbers(2, 3)

output:

5

Step 2: Return a meaningful value instead of None

When writing a function, make sure that it returns a meaningful value. Returning None is often a sign of a badly written function.

For example, if you have a function that calculates the area of a circle, you should make sure that it returns the area and not None.

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import math
 
def calculate_circle_area(radius):
    area = math.pi * radius ** 2
    return area

Now, if you call the calculate_circle_area function, it will return the area of the circle instead of None.

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calculate_circle_area(2)

output:

12.566370614359172

Step 3: Use assertion statements to check the return value of a function

In Python, you can use assertion statements to check if a function returns the expected value.

For example, if you have a function that calculates the area of a circle, you should use an assertion statement to check if the function returns the correct value.

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import math
 
def calculate_circle_area(radius):
    area = math.pi * radius ** 2
    return area
 
assert calculate_circle_area(2) == 12.566370614359172

If the assertion statement fails, it means that the function is returning the wrong value.

Conclusion

In conclusion, returning None in Python is often a source of frustration for developers. However, by following the steps outlined in this tutorial, you can avoid returning None and write better Python code.

Full Code Listing

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import math
 
def add_numbers(a, b):
    result = a + b
    return result
 
def calculate_circle_area(radius):
    area = math.pi * radius ** 2
    return area
 
assert add_numbers(2, 3) == 5
assert calculate_circle_area(2) == 12.566370614359172