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πŸ”— A fully implemented LinkedList made to work with general Microcontrollers and Arduino projects
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examples Added a sort() and an example. Nov 27, 2016
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This library was developed targeting Arduino applications. However, works just great with any C++.

Implementing a buffer for objects takes time. If we are not in the mood, we just create an array[1000] with enough size.

The objective of this library is to create a pattern for projects. If you need to use a List of: int, float, objects, Lists or Wales. This is what you are looking for.

With a simple but powerful caching algorithm, you can get subsequent objects much faster than usual. Tested without any problems with Lists bigger than 2000 members.


  1. Download the Latest release from gitHub.
  2. Unzip and modify the Folder name to "LinkedList" (Remove the '-version')
  3. Paste the modified folder on your Library folder (On your Libraries folder inside Sketchbooks or Arduino software).
  4. Reopen the Arduino software.

If you are here, because another Library requires this class, just don't waste time reading bellow. Install and ready.

Getting started

The LinkedList class

In case you don't know what a LinkedList is and what it's used for, take a quick look at Wikipedia::LinkedList before continuing.

To declare a LinkedList object

// Instantiate a LinkedList that will hold 'integer'
LinkedList<int> myLinkedList = LinkedList<int>();

// Or just this
LinkedList<int> myLinkedList;

// But if you are instantiating a pointer LinkedList...
LinkedList<int> *myLinkedList = new LinkedList<int>();

// If you want a LinkedList with any other type such as 'MyClass'
// Make sure you call delete(MyClass) when you remove!
LinkedList<MyClass> *myLinkedList = new LinkedList<MyClass>();

Getting the size of the linked list

// To get the size of a linked list, make use of the size() method
int theSize = myList.size();

// Notice that if it's pointer to the linked list, you should use -> instead
int theSize = myList->size();

Adding elements

// add(obj) method will insert at the END of the list

// add(index, obj) method will try to insert the object at the specified index
myList.add(0, myObject); // Add at the beginning
myList.add(3, myObject); // Add at index 3

// unshift(obj) method will insert the object at the beginning

Getting elements

// get(index) will return the element at index
// (notice that the start element is 0, not 1)

// Get the FIRST element
myObject = myList.get(0);

// Get the third element
myObject = myList.get(2);

// Get the LAST element
myObject = myList.get(myList.size() - 1);

Changing elements

// set(index, obj) method will change the object at index to obj

// Change the first element to myObject
myList.set(0, myObject);

// Change the third element to myObject
myList.set(2, myObject);

// Change the LAST element of the list
myList.set(myList.size() - 1, myObject);

Removing elements

// remove(index) will remove and return the element at index

// Remove the first object

// Get and Delete the third element
myDeletedObject = myList.remove(2);

// pop() will remove and return the LAST element
myDeletedObject = myList.pop();

// shift() will remove and return the FIRST element
myDeletedObject = myList.shift();

// clear() will erase the entire list, leaving it with 0 elements
// NOTE: Clear wont DELETE/FREE memory from Pointers, if you
// are using Classes/Poiners, manualy delete and free those.

Sorting elements

// Sort using a comparator function

Library Reference

ListNode struct

  • T ListNode::data - The object data

  • ListNode<T> *next - Pointer to the next Node

LinkedList class

boolean methods returns if succeeded

  • LinkedList<T>::LinkedList() - Constructor.

  • LinkedList<T>::~LinkedList() - Destructor. Clear Nodes to minimize memory. Does not free pointer memory.

  • int LinkedList<T>::size() - Returns the current size of the list.

  • bool LinkedList<T>::add(T) - Add element T at the END of the list.

  • bool LinkedList<T>::add(int index, T) - Add element T at index of the list.

  • bool LinkedList<T>::unshift(T) - Add element T at the BEGINNING of the list.

  • bool LinkedList<T>::set(int index, T) - Set the element at index to T.

  • T LinkedList<T>::remove(int index) - Remove element at index. Return the removed element. Does not free pointer memory

  • T LinkedList<T>::pop() - Remove the LAST element. Return the removed element.

  • T LinkedList<T>::shift() - Remove the FIRST element. Return the removed element.

  • T LinkedList<T>::get(int index) - Return the element at index.

  • void LinkedList<T>::clear() - Removes all elements. Does not free pointer memory.

  • void LinkedList<T>::sort(int (*cmp)(T &, T &)) - Sorts the linked list according to a comparator funcrion. The comparator should return < 0 if the first argument should be sorted before the second, and > 0 if the first argument should be sorted after the first element. (Same as how strcmp() works.)

  • protected int LinkedList<T>::_size - Holds the cached size of the list.

  • protected ListNode<T> LinkedList<T>::*root - Holds the root node of the list.

  • protected ListNode<T> LinkedList<T>::*last - Holds the last node of the list.

  • protected ListNode<T>* LinkedList<T>::getNode(int index) - Returns the index node of the list.

Version History

  • 1.1 (2013-07-20): Cache implemented. Getting subsequent objects is now O(N). Before, O(N^2).
  • 1.0 (2013-07-20): Original release


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