Python var is null

Check if a Variable is Null in Python

Null value is used in many programming languages but in Python, Null value does not exist. Instead of Null, the “None” is used in Python. The None value in Python indicates the absence of a value, and the values “0”, false, empty string, etc., do not represent “None”. In Python, there are various methods to verify if a variable is Null or not.

This write-up will provide a detailed guide for checking if a variable is Null in Python using the following methods:

Method 1: Using “is” Operator

“is” operator is used in the below-given Python program to check if the variable is none/null.

val = None if val is None: print('Input variable is null') if val is not None: print('Input variable is not null')

• A variable named “val” is assigned the “None” value.
• The “is” operator is used with the if statement to check if the variable’s value is null or not.
• The “is” operator will retrieve true if the value of variable “val” is equal to “None”. In such a case, the first if will be executed.
• If both the right and left sides of the “is” operator are unequal, then the second if block will be executed.

The above output shows that the variable’s value equals “None”.

Method 2: Using “==” Operator

In the example code given below, the “==” operator is utilized to verify if a variable is equal to None or not.

val = None if val == None: print('Input variable is null') if val != None: print('Input variable is not null')

• By using the “==” operator, it can be determined whether the given condition is equal to None.
• If the value is equal to None, then the statement written in the first “if” block will be executed; otherwise, the second “if” block will be run.

The above output verified that the input variable is Null/None.

Method 3: Using “if-else” Statement

In the example code given below, a simple “if-else” statement is used to check if the variable is Null or not:

val = None if val: print('val is not None') else: print('val is None')

In the above code snippet:

• The simple “if-else” statement is utilized to check if the variable’s value is “None”.
• The if-block will execute if the variable’s value is not equal to none.
• If the input variable is assigned with a None value, then the “else” block will execute.

The above output verified that the input variable’s value is “None”.

That’s it from this Python tutorial!

Conclusion

The “is” and “is not” operators, “==” and “!=” operators and “if-else” Statements are used to check if the variable is “Null/None” in Python. The “is” and “is not” operators are used along with the combination of the “if” statement to check the Null/None variable in Python. The “==” operator also works similarly to the “is” operator in Python, i.e., to check the Null variables. This article presented a detailed guide on how to check if a variable is Null in Python with numerous examples.

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How to Properly Check if a Variable is Not Null in Python

To check if a Variable is not Null in Python, we can use 3 methods:

Note: Python programming uses None instead of null.

1. Check if the Variable is not null [Method 1]

The first method is using «is«, «not» and «None» keywords. Let’s see the syntax, Then the examples.

Syntax

Example 1: Check String Variable

The above program returns True if the variable is not null. If null, it returns False.

As you can see, in the output, the program returns True.

Example 2: Check None Variable

The program returned False because my_var is None (null).

Example 3: Check Empty Variable

We got True Because my_var is empty, not None

2. Check if the Variable is not null [Method 2]

The second method for checking if the variable is not null is using the != operator + None keyword.

Syntax

Example 1: Check String Variable

The third method is the if condition. This method returns False if the variable is None or empty.

Syntax

Example 1: Check String Variable

This tutorial taught us how to check if the variable is not null. For more variable articles, check out:

Related Tutorials:

Recent Tutorials:

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How To Check If A Variable Is Null In Python

To check if a variable is Null in Python, there are some methods we have effectively tested: the is operator, Use try/except and the non-equal operator. Follow the article to better understand.

None and Null in Python

Nowaday, the keyword null is used in many programming languages to represent that the pointer is not pointing to any value. NULL is equivalent to 0. A newly created pointer points “miscellaneous” to a particular memory area. Assign the pointer to NULL to make sure it points to 0. Even though 0 is an invalid location, it’s easier to manage than when the pointer points to an area we don’t know.

In Python, there is no null but None .

None is a specific object indicating that the object is missing the presence of a value. The Python Null object is the singleton None .

In other words None in Python is similar to the Null keyword in other programming languages.

Check if a variable is Null in Python

Use the ‘is’ operator

The is operator is used to compare the memory addresses of two arguments. Everything in Python is an object, and each object has its memory address. The is operator checks if two variables refer to the same object in memory.

myVar = None # Check variable myVar is Null if myVar is None: print('The value of the variable myVar is None (null)')

The value of the variable myVar is None (null)

In the above example, I declared value = None and then used the is operator to check if value has None or not. If value is valid, then execute the if statement; otherwise execute the else statement.

Do not use the == operator to check for the value None . Because in some cases will lead to erroneous results.

Use try/except

Use try/except block to check if the variable is None .

The ‘if’ statement in ‘try’ to check variable ‘value’ exists and the value of ‘value’ is ‘none’

try: if myVar is None: print('The value of the variable myVar is None (null)') # Check name exists except NameError: print("The variable myVar does not exist")

The variable myVar does not exist

Use the non-equal operator

Another method to check if a variable is None is using the non-equal or != operator.

myVar = 1 if myVar != None: print('The variable is not null')

Summary

Here are ways to help you check if a variable is Null in Python. Or, if you have any questions about this topic, leave a comment below. I will answer your questions.

Maybe you are interested:

My name is Jason Wilson, you can call me Jason. My major is information technology, and I am proficient in C++, Python, and Java. I hope my writings are useful to you while you study programming languages.

Name of the university: HHAU
Major: IT
Programming Languages: C++, Python, Java

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How to check for null in Python

This article demonstrates the different ways available to check if a variable is NULL in Python.

What is the NULL keyword?

The NULL keyword is a fundamental part of programming. Being used in all popular programming languages like C, C++, or Java, it can essentially be represented as a pointer that points to nothing, or it simply ascertains the fact that the given variable is vacant.

What is NULL in Python?

Python operates differently from the other popular programming languages. Python defines the NULL object with the None keyword instead. These NULL objects are not valued as 0 in Python though. It does not hold any value whatsoever. This None keyword in Python is both an object and a None type data type.

How to check if a variable is NULL in Python?

Using the is operator to check if a variable is NULL in Python.

We can simply use the is operator or the = operator to check if a variable is None in Python.

The following code uses the is operator to check if a variable is NULL in Python.

The above code provides the following output:

We have made use of the is operator in this code to check the condition. Alternatively, we can also make use of the == operator to complete this task.

The following code implements the same by utilizing the == operator.

The above code provides the following output:

Using the if condition to check if a variable is NULL in Python.

We can simply use the if condition along with no additional operators in order to find out whether the given variable is None or not.

The following code uses the if condition to check if a variable is NULL in Python.

The above code provides the following output:

Using the not equal to operator to check if a variable is NULL in Python.

Another method to reveal whether a variable is None or not in Python is to utilize the != or the not equal to operator.

The following code uses the not equal to operator to check if a variable is NULL in Python.

The above code provides the following output:

These are the three methods that can be utilized to check whether the given variable is a None object or not.

Further, we can even check if the given variable is of the None data type as follows.

That’s all about how to check for null in Python.

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