What Is Null in Python? NoneType Object Explain 

If you have been doing programming for a good amount of time, then you might have heard about something called “Null.” Every programming language has different kinds of data types that represent different sorts of data, and null in Python is one of them. 

Many beginners may mistake null for zero (0) because zero means nothing and null represents nothing. That is not the case, as zero itself is a value, whereas null is a totally different concept. Today in this article, we will try to explain null, what it means, and what the use of this concept is in Python. 

What is Null? 

In short, “null” means the absence of value. Say you wrote a program that was supposed to return an integer value, but there is no integer value. Whenever this kind of absence is present in the code, the code returns something called null. 

Null is not null in Python, what do I mean by this? Many programming languages might return null when the previous example we stated happens. In the case of Python, null is represented with the None keyword.

To show you an example, here is some code where we called a function named function1() and did not put anything inside it. Next, we have called the function that will return the value, As the function has no value we are expecting the function to return the None type.

def function1():
   pass
function1()
print(function1()))
Code language: Python (python)

None type can be a great use when you want to check some missing parameters in your code.

Usage of Python Null Object (None)

Let us check on some used cases where you might want to use None type object

Regex

A popular concept in Python programming is the regular functions or re which creates some kind of search pattern. We use this module from python to check whether something is inside the string or perform similar searches like this. 

To do this we use a ‘re.search’ command that searches what you are looking for. What happens when what you are trying to find is not there? Regex returns a Null object or none when it fails to find the data you are looking for. 

Dictionary

If you have done coding in JS before then you might have heard about something called an “object”. Python also has something similar to objects from JS that is not known as objects here, instead, Python calls it a dictionary. 

Values inside that dictionary are called “keys” and often you have to access one of those keys in your program. Sometimes, you might forget to add one key and when you search for a non-existing key inside the dictionary, it will return a none type value. 

Functions

Functions are something that does some work and returns the value if we want to explain functions in the simplest term. In the previous section, we showed you an example where we wrote a function with nothing and tried to return something from it. 

In real-world projects, you might expect your function to return something and you can check whether it can return it or not. If your function is failed to do so then it will return a null or none type in the output.  

Declaring a Null Type in Python 

In programming languages like C or C++, you have to declare a data type before you want to use them. You don’t have to go through a declaration or some other things in Python, you can just assign the value inside the variable and get your job done with it. 

Here is an example where we put a null-type object inside a variable and print its value.

def var1 = none
print(var1)
Code language: Python (python)

Even if you put nothing inside the variable, Python automatically puts value inside the variable. So, if you just declare the variable and assign nothing to it then you should expect to get a None value in return but that is not the case. 

Why Python does not show none as an output in that case? Python variables, like some other languages, do not need a declaration before using them. You can just take a variable and assign something to it. If you don’t assign anything to any variable Python will not take it as a variable in the first place and will throw an error to it. 

None as Default Parameter

Say you are writing a code or function where it will take some value inside a variable and store it. Your code does not require that variable to hold information all the time, At that time you might want to set a default value as None to that variable, and it is very common. 

Yes, putting nothing inside the variable might do the same but often it creates a problem. The best practice is to set a default value to your variable, None type is the best data type for this fact. Here is a code example of how you can set a default value. 

def func(new, start=None):
    if start is None:
        start=[]
    start.append(new)
    return start
Code language: Python (python)

This is a portion of a code, notice the structure and what the code is doing. Here, we declared a function func() and set two parameters. One will take a new value and another parameter will create an array will no value set as default.

In the condition, we set if the out start parameter has no value it will create an array. You see we have set a default value for the start parameter as none.

None as The Null Value

Let us make None a valid input value, shall we? What if you wrote a code where you can input None as a valid argument? So, let us write a code where it will append a none value when there is nothing to append. 

class dont: pass
def func(new=dont, start=None):
    if start is None:
        start=[]
    if new is not dont:
        start.append(new)
    return start
func(None)    
print(func()))
Code language: Python (python)

When you run this program, you will find an empty array as the output. You might have noticed that we put None as a value inside the code, So yes there is a value inside the array and it is None.

Conclusion 

If you have worked with Binary objects in Python then you might find some similarities in None with true and false. As a Python programmer, you must have a clear understanding of all kinds of available objects. I hope you now have a clear understanding of the topic and are ready to extend your knowledge furthermore.