The 0 and None are automatically cast to False in Python, so a different solution must be used to check if a value is not None or is 0. The data type of None in Python is NoneType.
To verify that, write this code:
print(type(None))
Output
<class 'NoneType'>
Comparisons to singleton objects like None should always be done with is or is not operators and never the equality operators.
Python check if none
- By using is operator to check if a variable is None.
- Using isinstance() method.
- By using Dictionary.
- Using try/except block.
To check if a variable is None in Python, use the is operator. With the help of the if statement, we can check whether the variable is None and if it is, then if statement executes otherwise, else will be executed.
Python code for checking None in Python
var = None
kb = 5
if(var is None):
print("The var is None")
if(kb is not None):
print("The kb is not None")
Output
The var is None
The kb is not None
In this example, we used is and is not operators to check whether the variable is None. The is not operator is precisely the opposite of None, and it is a kind of negative check for a variable. This is the safest and easiest way to check if a variable is None in Python.
Using Python isinstance() method
The isinstance() is a built-in Python method that checks whether an object is of a specific data type or not. For example, comparing type(None) with None assigned variable using isinstance() returns whether it is None or not.
The isinstance() method returns a boolean value which is either True or False based on the output of the checking variable.
var = None
kb = 5
print(isinstance(var, type(None)))
print(isinstance(kb, type(None)))
Output
True
False
You can see that it returns True when the variable is None and False when it is an integer.
Using a Dictionary to Check if a Variable Is None
Dictionary stores data in key-value pairs. We will check if the variable is None.
data = None
dict = {None: 'The variable is None'}
print(dict[data])
Output
The variable is None
This approach is not suitable compared to previous methods.
Using a try and except block
To deal with exceptions in Python, use the try…except block that may raise exceptions. For example, Python will raise the NoneType exception if the variable is None and it is being operated.
If we put the variable we suspect is None put in the try block, and if the variable is None, then the exception will be raised, which is caught in the catch block.
data = None
kb = 21
try:
sum = data + kb
except:
print("One variable is None")
Output
One variable is None
That’s it for this tutorial.
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Krunal Lathiya is a Software Engineer with over eight years of experience. He has developed a strong foundation in computer science principles and a passion for problem-solving. In addition, Krunal has excellent knowledge of Data Science and Machine Learning, and he is an expert in R Language. Krunal has experience with various programming languages and technologies, including PHP, Python, and JavaScript. He is comfortable working in front-end and back-end development.