Скачать или смотреть How to Properly Add a Node to a Linked List in Python: Solving the AttributeError

Discover the simple fix to the common `AttributeError` when adding a new node in a Python Linked List. Learn how to use classes effectively.
---
This video is based on the question https://stackoverflow.com/q/63406182/ asked by the user 'Chadmeistr' ( https://stackoverflow.com/u/13594151/ ) and on the answer https://stackoverflow.com/a/63406316/ provided by the user 'Surya Lohia.' ( https://stackoverflow.com/u/6166414/ ) 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: Linked Lists - adding new node doesn't work

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 the Linked List Node Addition Error

Linked lists are a fundamental data structure in computer science, and they can be tricky when you're just starting out. A common issue that many beginners face is related to adding new nodes to a linked list. Recently, one of the learners encountered an AttributeError when attempting to add a new node, highlighting an important lesson in handling classes and objects in Python.

Here's the purpose of this guide: to clarify why this error occurs and provide a straightforward solution. If you've found yourself in a similar predicament, you're in the right place!

The Problem: AttributeError When Adding a Node

Let’s take a look at the code that caused the issue:

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

When run, this code snippet throws the following error:

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

This indicates that the program is attempting to access a property (next) that does not exist on the string object you passed into the add_first method.

The Solution: Properly Creating Nodes

To properly add a new node to the linked list, you need to ensure that a Node object is created from your input before linking it to the list. Here's the corrected version of the add_first method:

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

Explanation of the Solution

Create a Node Instance: The function accepts a single value s and creates a new instance of the Node class using this value.

Linking the Nodes: Before setting the new node as the head of the list, the current head is connected to the next of the new node. This preserves the existing linked structure of the list.

Update the Head: Finally, the head of the list is updated to this new node which has just been added.

Updated Example

Here's how your final code would look after correcting the add_first method:

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

Conclusion

Adding nodes to a linked list is an essential skill for any programmer. By understanding the interaction between classes and instances in Python, you can avoid common pitfalls like the AttributeError. Remember, when adding a new node, always create a Node object for the data you want to insert into your linked list!

Now you’re equipped to enhance your linked list with confidence. Happy coding!