Collections in C# Language

In C#, collections are an essential part of any developer’s toolkit. They provide a way to store and manipulate groups of data, making it easier to manage, access, and manipulate information in your applications. In this post, we’ll explore some of the most commonly used collection types in C# and provide examples of how to work with them.

Arrays

Arrays are one of the simplest and most widely used collection types in C#. They are a fixed-size collection of elements of the same type.

int[] numbers = new int[5] { 1, 2, 3, 4, 5 };

Lists

Lists are dynamic arrays in C# that can grow or shrink in size. They are part of the System.Collections.Generic namespace.

List<string> names = new List<string>() { "Alice", "Bob", "Charlie" };
names.Add("David");

Dictionaries

Dictionaries are key-value pairs where each key maps to a value. They are also part of the System.Collections.Generic namespace.

Dictionary<string, int> ageLookup = new Dictionary<string, int>();
ageLookup["Alice"] = 25;
ageLookup["Bob"] = 30;

Sets

Sets are collections that contain unique elements. Duplicates are automatically eliminated.

HashSet<int> uniqueNumbers = new HashSet<int>() { 1, 2, 3, 3, 4, 5 };

Queues

Queues are used to manage a first-in, first-out (FIFO) collection of items.

Queue<string> queue = new Queue<string>();
queue.Enqueue("First");
queue.Enqueue("Second");
string item = queue.Dequeue(); // "First"

Stacks

Stacks are used to manage a last-in, first-out (LIFO) collection of items.

Stack<string> stack = new Stack<string>();
stack.Push("First");
stack.Push("Second");
string item = stack.Pop(); // "Second"

Collections in LINQ

C# also provides Language-Integrated Query (LINQ) for querying and manipulating collections. LINQ allows you to perform powerful operations on collections, such as filtering, sorting, and projection.

List<int> numbers = new List<int>() { 1, 2, 3, 4, 5 };
var evenNumbers = numbers.Where(x => x % 2 == 0).ToList();