Python null value

In Python, there is a special value called “None” that represents the absence of a value or the null value. It is used to indicate that a variable does not have any assigned value. None is a built-in constant, and it is of the type “NoneType.”

Here’s the syntax for using None in Python:

# Assigning None to a variable
my_variable = None

Checking if a variable is None

if my_variable is None:
    print("my_variable is None")
else:
    print("my_variable has a value")

The function that returns None

def my_function():
    # Some code here...
    return None

result = my_function()
if result is None:
    print("The function returned None")
else:
    print("The function returned a value")

In the code above, None is assigned to the variable my_variable, and then we check if it’s None using the is keyword. The function my_function explicitly returns None, which is later checked in the if statement.

Note: Use is when checking for None, as it ensures you are comparing the identity of the object and not just its value. The is operator checks if two variables refer to the same object in memory, while the == operator checks if the values of the two objects are the same.

Python null value example

Here’s an example that demonstrates the use of None as the null value in Python:

# Function square root of a number (positive numbers only)
def find_square_root(number):
    if number >= 0:
        return number ** 0.5
    else:
        return None

# Test cases
n1 = 16
n2 = -25

result1 = find_square_root(n1)
if result1 is None:
    print("The square root of", n1, "is not defined for negative numbers.")
else:
    print("The square root of", n1, "is", result1)

result2 = find_square_root(n2)
if result2 is None:
    print("The square root of", n2, "is not defined for negative numbers.")
else:
    print("The square root of", n2, "is", result2)

Output:

In this example, we have a function find_square_root that calculates the square root of a given number. However, it is designed to handle only positive numbers. If a negative number is passed to the function, it returns None.

Note: IDE: PyCharm 2021.3.3 (Community Edition)

Windows 10

Python 3.10.1

All Python Examples are in Python 3, so Maybe its different from python 2 or upgraded versions.