Скачать или смотреть Understanding Why Your Python Function Returns None at the End

Discover why your Python function outputs `None` and how to fix it by organizing your print statements correctly.
---
This video is based on the question https://stackoverflow.com/q/70696518/ asked by the user 'almuhannad_01' ( https://stackoverflow.com/u/17490743/ ) and on the answer https://stackoverflow.com/a/70696690/ provided by the user 'Thekingis007' ( https://stackoverflow.com/u/17209725/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Why in this program print None in output?

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Understanding Why Your Python Function Returns None at the End

If you've been working with Python, you may have encountered a situation where your function prints out None at the end of its output. This can be confusing, especially when everything seems fine in your code. In this guide, we'll dissect one specific case to illustrate why this happens and how to rectify the issue effectively.

The Problem

Let's consider the following Python function that is designed to print every other element from a list:

[[See Video to Reveal this Text or Code Snippet]]

When you run this code, you might be surprised to find that it prints None after the intended output. So, why is that happening?

Understanding None in Python

In Python, when a function does not have a return statement, it implicitly returns None. In the function skip_elements, the absence of a return statement means that it returns None after it completes its task. Thus, when you call print(skip_elements(...)), what gets printed is this None value, following the actual output of your function.

The Solution: Correcting the Code

To resolve this issue, you need to remove the print statement that wraps the function calls. Instead, just call the function directly without attempting to print its return value. Here’s how to modify the code:

[[See Video to Reveal this Text or Code Snippet]]

Updated Output

When you run the revised code snippet, the output will now be:

[[See Video to Reveal this Text or Code Snippet]]

Key Takeaways

Functions in Python return None by default if they don’t have a return statement.

If you use print to display the result of such a function, you'll see None printed after the intended output.

You can simply call the function without wrapping it with print to avoid printing None.

By understanding these principles, you can write more effective Python code without confusion over unexpected None outputs. If you face similar issues in the future, remember to examine how and where you are printing your function calls!