Difference Between an Array and a List in C#

Array

An array stores a fixed amount of variables of the same data type(string, int, char). It is strongly typed and belongs to the System.Array Namespace.

There are 3 types of arrays:

• single dimensional
• Multi-dimensional
• Jagged

The most commonly used is the single-dimensional array.

List

A List is a dynamic array that increases and decreases according to data size. It stores a generic collection of objects. It is not strongly typed(strings and numbers can be in a List) and belongs to the System.Collection namespace.

How to instantiate an array and a List

Array

To instantiate an array, specify the variable type(string, int, char ), followed by the array name and then the array length.

using System.Array; // import array class

int[] numberArray

numberArray = new int[] { 5, 3, 2, 9};

List

To instantiate a List, call the List class, followed by the type in an angled bracket, and then the List name. The new keyword instantiates the List Class.

using System.Collection; // import List class

List<int> listExample = new List<int>{5, 3, 2, 9};

// shorter version
var listExample = new List<int> {5, 3, 2, 9};

Can I instantiate an empty array or List?

Array

You can create an empty array by setting the length to [0]. To instantiate the Array, You must specify the array length.

Use Array.Empty<int>() to instantiate an empty array instead of creating an empty Array with length[0].

var newArray = new int[0] 

// recommended

var newArray = Array.Empty<int>();

List

Yes, you can instantiate an empty list. Because of its dynamic nature, the List will automatically increase or decrease in size as needed.

var newList = new List<int>();

How to check the length of an Array and a List

Array

Length returns the total number of elements in an array

string[] total = new string[] {"love", "live", "life", "fly", "soar"}

Console.WriteLine(total.Length) // 5

List

Count returns the total number of elements in a list

var total = new List<string> {"love", "live", "life", "fly", "soar"}

Console.WriteLine(total.Count()) //5

When to use an Array vs A list

If the data size is fixed and you know the size of the data, or you want to optimise for a specific reason, then an Array can come in handy. If the operation involves adding and removing data, use a List. It requires no resizing.

Conclusion

A List is the preferred choice when it comes to choosing to use either an Array or a List, even when no data resizing is needed. Most operations you want to use an Array for can be done with a List.