What is Indexer in C#?

Introduction

An indexer in C# allows instances of a class or struct to be indexed like arrays. This means you can access elements using array-like syntax without explicitly specifying a type or instance member. Indexers are defined using this keyword, and they can have both get and set accessors.

Here’s a simple example.

public class SampleCollection<T>
{
    private T[] arr = new T[100];

    public T this[int i]
    {
        get => arr[i];
        set => arr[i] = value;
    }
}

In this example, SampleCollection is a generic class with an indexer that allows you to get and set elements using an index, just like an array12.Example.

This example demonstrates a simple string collection with an indexer.

public class StringCollection
{
    private string[] strings = new string[10];

    public string this[int index]
    {
        get => strings[index];
        set => strings[index] = value;
    }
}

You can use this class like an array.

var collection = new StringCollection();
collection[0] = "Hello";
collection[1] = "World";
collection[2] = "My name is Arpit";

Console.WriteLine($"{collection[0]} {collection[1]}, {collection[2]}"); // Output: Hello World, My name is Arpit

The output will be,