Difference Between an Array and a List in C#

Published on Wednesday, 23 January 2023

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.

1using System.Array; // import array class
2
3int[] numberArray
4
5numberArray = new int[] { 5, 3, 2, 9};
6
7

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.

1using System.Collection; // import List class
2
3List<int> listExample = new List<int>{5, 3, 2, 9};
4
5// shorter version
6var listExample = new List<int> {5, 3, 2, 9};
7
8

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].

1var newArray = new int[0] 
2
3// recommended
4
5var newArray = Array.Empty<int>();
6
7

List

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

1
2var newList = new List<int>();
3
4

How to check the length of an Array and a List

Array

Length returns the total number of elements in an array

1
2string[] total = new string[] {"love", "live", "life", "fly", "soar"}
3
4Console.WriteLine(total.Length) // 5
5

List

Count returns the total number of elements in a list

1var total = new List<string> {"love", "live", "life", "fly", "soar"}
2
3Console.WriteLine(total.Count()) //5
4

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.

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