# Check if a List is Empty or Not in Python Using len() Function

(Last Updated On: 27/09/2023)

In this blog post, we will explore how to check if a list is empty or not in Python using len() function. We will walk through the step-by-step logic and operations involved in this process. Whether you are a beginner or an experienced Python programmer, understanding this technique will prove valuable in your programming journey.

In Python, working with lists is a common task, and often we come across situations where we need to determine whether a list is empty or not. Python provides us with a simple and convenient way to check the emptiness of a list using the len() function. The len() function returns the number of elements in a list, and by comparing the length of the list to zero, we can easily determine if the list is empty.

So, let’s dive into the details and learn a Python program to check if a list is empty or not using the len() function.

## Python Program to Check if a List is Empty or Not Using len() Function

```# Check If a List is Empty in python Using len() function

# empty list
list = []

# Checking whether the list size is equal to 0
if len(list) == 0:
print('Empty list')
else:
print('Not Empty list')
```

#### Code Explanation

• Creating an Empty List

To begin, we create an empty list by assigning an empty pair of square brackets to a variable, such as list = [].

• Checking the List Size

We use the len() function to determine the size of the list, i.e., the number of elements it contains. To check if the list is empty, we compare the length of the list to 0 using the equality operator (==). The code snippet if len(list) == 0: checks if the length of the list is equal to 0.

• Displaying the Result

If the length of the list is indeed 0, we print the message “Empty list” using the print() function. Otherwise, if the length of the list is not 0, we print the message “Not Empty list”.

#### Output:

The output of the code depends on whether the list is empty or not. If the list is empty, the output is:

``Empty list``

On the other hand, if the list is not empty, the result will be:

``Not Empty list``

### Here are a few alternative methods to check if a list is empty

In Python, there are multiple ways to check if a list is empty.

• Using the not operator:

You can use the not operator to check if a list is empty. This method is concise and straightforward. It directly checks the truthiness of the list without explicitly comparing its length.

• Directly comparing with an empty list:

Another approach is to compare the list directly with an empty list. This method explicitly checks if the list is equal to an empty list and is intuitive to understand.

• Using the bool() function:

You can also use the bool() function to check the boolean value of the list. It converts the list into a boolean value (True or False) based on its truthiness.

Using the len() function makes the code more readable and easier to understand for other developers. It follows a standard convention and is familiar to most Python developers. If you need to check the size of different types of containers, using the len() function provides consistency across your code.

In conclusion, we have seen how to check if a list is empty in Python using the len() function. By using the len() function to determine the length of a list and comparing it to 0, we can easily identify whether the list is empty or not. This technique provides a straightforward and reliable way to handle empty lists in Python programs.

By understanding this approach, you can effectively validate the emptiness of a list and make informed decisions based on its state. This knowledge is valuable in various scenarios where you need to handle empty lists gracefully and ensure your program’s logic operates correctly.

#### FAQs to check if a list is empty using the len() function

How does the len() function work?

The len() function takes a sequence (such as a list) as an argument and returns the number of elements in that sequence. It calculates the length of the sequence by iterating over its elements and counting them.

Why do we compare the length of the list to 0 using the equality operator?

By comparing the length of the list to 0, we can check if the list is empty. If the length is 0, it means the list does not contain any elements, indicating that it is empty.

What happens if the list is empty?

If the list is empty, the condition len(list) == 0 evaluates to True. In this case, the program will print the message “Empty list” to indicate that the list is empty.

Is there any performance impact in using len() to check for an empty list?

No, using the len() function to check for an empty list has a negligible performance impact. The len() function has a time complexity of O(1), which means its execution time does not depend on the size of the list.

Can we use this method to check if other data structures, such as strings or tuples, are empty?

Yes, the same len() function can be used to check if other sequences, including strings and tuples, are empty. The approach remains the same: comparing the length of the sequence to 0.