How to check for None in Python variables

There are three ways you can check for a None value in Python:

1. Using the is operator keyword
2. Using the equality operator ==
3. Using the isinstance() function

The None value in Python is used to signify an “empty” value. It’s similar to the NULL value in other programming languages.

This tutorial shows how to use the three methods mentioned above to check if a variable is None.

1. Using the is operator keyword

The is operator keyword is used to check if the two operands surrounding the operator refer to the same object or value.

This operator can be used to check if a variable has a None value. Suppose you want to check the value of the x variable as follows:

x = "abc"

result = x is None

print(result)  # False

The is operator returns True when the two operands refer to the same object. Otherwise it returns False.

You can use this operator in an if statement to check for the value of a variable:

x = "abc"

if x is None:
    print("Value of x is None")
else:
    print("x is not None")

The else statement is optional, and you can omit it if you want the program to do nothing when the variable value is not None.

2. Using the equality == operator

The equality == operator checks whether the two operands surrounding the operator are inherently equal.

Like the is operator, you can combine this operator with an if statement to check whether a variable contains None:

x = "abc"

if x == None:
    print("Value of x is None")
else:
    print("x is not None")

However, most people would recommend you to use is instead of == because the is keyword is faster than the equality operator.

The is keyword doesn’t check for the value of the operands. It simply sees if the two operands point to the same object.

You can test this by comparing two empty arrays as follows:

x = []
y = []

print(x is y)  # False
print(x == y)  # True

Although both variables have the same value, they are pointing to different objects, so the is keyword returns False while the equality operator returns True.

3. Using the isinstance() function

The isinstance() function is used to check whether an object is an instance of a specific class.

The function returns true when the object is an instance of the class you specified. You can use this function to check if a variable is None as follows:

x = None

res = isinstance(x, type(None))
print(res)  # True

The isinstance() function can be used as an alternative when you need to check whether a variable is assigned a None value.

Conclusion

This tutorial shows you three simple and effective ways to check whether a variable is None or not. The is keyword is the most simple and straightforward, and it’s the most popular way to check for a None value.

I hope this tutorial helps. See you in other tutorials! 🙌