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

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:

  1. Method 1: variable is not None
  2. Method 2: variable != None
  3. Method 3: if variable:

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

variable is not None

Example 1: Check String Variable

my_var = "Hello Python" # 👉️ String Variable 

# 👇 Check if my_var is not Null
if my_var is not None: # 👉️ Check if my_var is not None (null)
    print(True)
else:
    print(False)

Output:

True

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

my_var = None # 👉️ None Variable 

# 👇 Check if my_var is not Null
if my_var is not None: # 👉️ Check if my_var is not None (null)
    print(True)
else:
    print(False)

Output:

False

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

Example 3: Check Empty Variable

my_var = "" # 👉️ Empty Variable 

# 👇 Check if my_var is not Null
if my_var is not None: # 👉️ Check if my_var is not None (null)
    print(True)
else:
    print(False)

Output:

True

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

variable != None

Example 1: Check String Variable

my_var = "Hello Python" # 👉️ String Variable 

# 👇 Check if my_var is not Null
if my_var != None: # 👉️ Check if my_var is not None (null)
    print(True)
else:
    print(False)

Output:

True

Example 2: Check None Variable

my_var = None # 👉️ None Variable 

# 👇 Check if my_var is not Null
if my_var != None: # 👉️ Check if my_var is not None (null)
    print(True)
else:
    print(False)

Output:

False

Example 3: Check Empty Variable

my_var = "" # 👉️ Empty Variable 

# 👇 Check if my_var is not Null
if my_var != None: # 👉️ Check if my_var is not None (null)
    print(True)
else:
    print(False)

Output:

True

3. Check if the Variable is not null [Method 3]

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

Syntax

if variable:

Example 1: Check String Variable

my_var = "Hello Python" # 👉️ String Variable 

# 👇 Check if my_var is not Null
if my_var: # 👉️ Check if my_var is not None (null)
    print(True)
else:
    print(False)

Output:

True

Example 2: Check None Variable:

my_var = None # 👉️ None Variable 

# 👇 Check if my_var is not Null
if my_var: # 👉️ Check if my_var is not None (null)
    print(True)
else:
    print(False)

Output:

False

Example 3: Check Empty Variable

my_var = "" # 👉️ Empty Variable 

# 👇 Check if my_var is not Null
if my_var: # 👉️ Check if my_var is not None (null)
    print(True)
else:
    print(False)

Output:

False

Conclusion

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