The Key Differences Between an Array and a Linked List
When it comes to data structures, two commonly used ones are arrays and linked lists. While they may seem similar at first, there are fundamental differences that set them apart. In this article, we will explore those differences, and examine some common use cases for each.
Arrays
Arrays, typically considered a primitive data structure, are essentially a collection of values, all of the same data type, stored in contiguous memory blocks. They allow for random access, which means you can find and retrieve a specific element with a simple index. This makes arrays efficient for accessing data with a known location, like the first or last element. They also have a fixed size, which cannot be changed once they are created, making them predictable in terms of memory allocation.
However, this predictability can also be a drawback. If you need to add or remove elements from an array, you must create a new, larger or smaller array and copy the elements over. This can be time-consuming and resource-intensive, and it means arrays may not be the best choice for situations where the size of the data structure needs to change frequently.
Linked Lists
Linked lists, on the other hand, are more flexible. They are made up of nodes, each containing a value and a pointer to the next node in the list. Unlike arrays, linked lists do not require contiguous memory blocks, which means they can grow or shrink as needed. Linked lists also allow for constant time insertions and deletions at any position, as you only need to update the node’s pointers.
However, linked lists do not offer constant time random access. In order to find an element, you must traverse the list sequentially, starting from the head or the tail. This can be slower than accessing an element in an array, especially for large lists. Additionally, because nodes in a linked list are not stored contiguously, they may take up more memory than an array with the same number of elements.
Choosing Between Arrays and Linked Lists
So, when should you use an array versus a linked list? It depends on your specific use case. If you need constant time access to elements with a known location, and the size of the data structure will not change frequently, an array may be the better choice. However, if you need a flexible data structure that can grow or shrink easily, and you do not need constant time random access, a linked list may be the better choice.
In conclusion, while arrays and linked lists may seem similar on the surface, under the hood they have very different characteristics. By understanding the differences, and knowing how to leverage them, you can make informed decisions about which data structure to use for your specific needs.
Table difference between array and linked list
| Parameter | Array | Linked List |
|---|---|---|
| Definition | Array is a collection of elements stored in a contiguous memory location. | Linked List is a collection of nodes where each node points to the next node using a pointer field. |
| Memory Allocation | Array needs a fixed amount of memory which is allocated at compile time. | Linked List requires dynamic memory allocation where each node can be allocated separately. |
| Size and Capacity | The size of an array is fixed, once declared it cannot be expanded or shrunk. | Linked List can grow or shrink dynamically as per the requirement. |
| Traversal | Elements can be accessed using index values, and traversing is faster. | Traversal is slower than an array because nodes are not stored in contiguous memory locations. |
| Insertion and Deletion | Insertion and deletion operations are complex and time-consuming as elements need to be shifted or relocated. | Insertion and deletion operations are faster and efficient. |
| Sorting | Sorting an array is easy and efficient. | Sorting a linked list is complex and time-consuming. |