Python Null Equivalent Syntax

Dealing with missing or undefined values is a common task for developers in Python. Unlike some other programming languages that use a specific keyword like “null” to represent the absence of a value, Python employs the concept of “None” as its null equivalent. Additionally, the concept of “NaN” (Not a Number) is often used when working with numerical data. In this article, we will delve into the various aspects of the null equivalent syntax in Python, explore the use of “None”, “NaN”, and other strategies to handle the missing or undefined values.

Example 1: Understanding “None”

The primary null equivalent in Python is “None”. It is a special constant that represents the absence of a value or a null value. In Python, functions without a return statement implicitly return “None”.

Here’s a simple example:

def no_return():



result = no_return()



In the provided Python code snippet, we define a function named “no_return” using the “def” keyword. However, the function body consists only of the “pass” statement, indicating that it doesn’t execute any specific operations or return any values. Then, the code calls the “no_return” function and assigns its result to the variable named “result”. Since the “no_return” function has no return statement, it implicitly returns the special value of “None” in Python. Thus, the “result” variable holds the value of “None” after the function call.

Finally, the code prints the value of “result” using the “print” function. As expected, the output of this code is “None”.

Example 2: Handling “None” in Conditional Statements

When working with programming, understanding how to handle the special value of “None” in conditional statements is essential for creating an effective code. “None” often represents the absence of a value or the lack of a specific result. We can use this knowledge in conditional statements to decide whether a variable is set to “None” or has a meaningful value.

We can employ the conditional statements, such as “if” and “else”, to check for the presence or absence of “None” and respond accordingly. For instance, when a function returns “None” to indicate an error or an invalid state, the code can use the conditional statements to identify this condition and take appropriate actions such as logging an error message or prompting the user for valid input.

Here is the example code:

def process_data(data):

  if data is None:

     print("Error: No data provided.")



     print("Data processed successfully.")


input_data = None



In the provided code snippet, we define a function called “process_data” that takes a parameter named “data”. The function begins with a conditional statement which checks if the input data is equal to “None”. If this condition is true, it prints an error message which states “Error: No data provided”. On the other hand, if the input data is not “None”, the code proceeds to the “else” block, indicating that the data is valid. Inside the “else” block is a comment which indicates that this is the section where the data processing occurs.  Following the function definition, the “input_data” variable is assigned the value of “None”. Subsequently, the “process_data” function is called “input_data” as its argument. In this specific instance, since the “input_data” is set to “None”, the output of running this code is the “Error: No data provided” error message.

Here is the generated output of this code:

Example 3: Handling the Undefined Numerical Values

In programming, handling undefined or missing values is a critical aspect. One such representation of undefined numerical values is “NaN” which means “Not a Number”. NaN is often encountered when a mathematical operation or function is undefined or encounters an invalid input.

Regarding numerical computations and data analysis, the concept of “NaN”, which stands for “Not a Number”, plays a pivotal role. Handling NaN is critical to ensuring the accuracy and reliability of numerical computations as it allows the programmers to identify and manage the situations where the computations yield unexpected or undefined results.

Let’s illustrate this with a simple code snippet:

import math

result = 0 / 0

if math.isnan(result):

   print("The result is undefined (NaN).")


   print(f"The result is: {result}")


In the provided code snippet, we begin by importing the math module that is necessary for mathematical operations and functions. We then attempt a division operation where we set the result to the result of dividing zero by zero. This particular operation normally raises a “ZeroDivisionError” because the division by zero is undefined. However, we employ a subsequent check using “math.isnan(result)” to determine if the result is the special floating-point value of “NaN” which stands for “Not a Number”.

If you want to avoid the error, you could modify the code as follows:

import math


   result = 0 / 0

except ZeroDivisionError:

   result = math.nan

if math.isnan(result):

   print("The result is undefined (NaN).")


   print(f"The result is: {result}")


In this concise code snippet, we utilize a “try” and “except” blocks to handle a potential “ZeroDivisionError” that may arise from attempting to divide zero by zero. Inside the “try” block, we set the “result” variable to the result of the division operation. If a “ZeroDivisionError” occurs, the “except” block is triggered, and we explicitly assign the “result” with the value of “math.nan”, indicating a result that is “Not a Number”. Following this, we check if the result is NaN using math.isnan(result’). If the result is indeed NaN, the code prints a message stating that the result is undefined. Otherwise, it prints the actual numerical result.

Example 4: The Optional Type Hint

With the introduction of type hints in Python, the “Optional type” hint from the typing module often indicates that a variable can either be of a specified type or “None”.

Here is the code:

from typing import Optional


def greet(name: Optional[str] = None) -> str:

  if the name is None:

     return "Hi, Unknown!"


     return f"Hello, {name}!"





This code defines a Python function called “greet” that takes an optional parameter name of type string, defaulting to “None”. The function returns a greeting message, either a generic one if the name is not provided (None) or a personalized one with the provided name. The “Optional type” hint indicates that the parameter can either be a string or “None”. The two function calls at the end demonstrate its usage: the first call prints a generic greeting and the second call prints a personalized greeting for a person named “Adam”.


This article explored the null equivalent syntax in Python, focusing on the handy use of “None” as the primary representation of the missing or undefined values. We learned how “None” is employed in conditional statements to check for the presence of a value, and delved into the realm of numerical computations with “NaN” to handle the undefined numerical results. The Optional Type Hint was introduced as a valuable tool to enhance the code readability and catch the potential errors when dealing with variables of a specified type or “None”.

About the author

Omar Farooq

Hello Readers, I am Omar and I have been writing technical articles from last decade. You can check out my writing pieces.