How To Compare To Null In Python

In Python, if we want to check whether a variable is None, we usually use the keyword is instead of ==. In this tutorial, we’ll understand how to compare variables to None and learn about other relevant concepts as well. Let’s dive in!

Step 1: Basic Comparison to None Using ‘is’

In Python, we can use the is keyword to check if a variable is equal to None. The is operator checks for object identity instead of object equality. Since None is a singleton object, it’s always better to use the is keyword. Here’s an example:

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a = None
 
if a is None:
    print("a is None")
else:
    print("a is not None")
 
a is None

Step 2: Comparing Variables Using ‘==’ Operator

Although the == operator is typically used for comparing values, it’s important to understand why this operator might not be suitable for comparing with None.

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b = None
 
if b == None:
    print("b is None")
else:
    print("b is not None")
 
b is None

The code works, but it’s generally not recommended to use == for comparing with None because the == operator checks for object equality, not identity. In the case of None, it’s better to use the is keyword, as suggested in Step 1.

Step 3: Comparing Variables Using ‘is not’ and ‘!=’ Operators

To check if a variable is not equal to None, we can use the is not keyword or != operator. Let’s look at examples of both ways:

Using is not:

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c = 5
 
if c is not None:
    print("c is not None")
else:
    print("c is None")
 
c is not None

Using !=:

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d = 5
 
if d != None:
    print("d is not None")
else:
    print("d is None")
 
d is not None

While both methods may work, it’s still recommended to use the is not keyword when comparing a variable to None.

Full Code

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a = None
if a is None:
    print("a is None")
else:
    print("a is not None")
 
b = None
if b == None:
    print("b is None")
else:
    print("b is not None")
 
c = 5
if c is not None:
    print("c is not None")
else:
    print("c is None")
 
d = 5
if d != None:
    print("d is not None")
else:
    print("d is None")
 
a is None
b is None
c is not None
d is not None

Conclusion

In this tutorial, we learned how to compare a variable to None in Python using different operators, such as is, ==, is not, and !=. We found that the best practice is to use the is keyword when comparing a variable to None. Understanding these techniques will help you write cleaner and more efficient Python code.