What is Indexers in C# .Net?

What is Indexers in C# .Net?

In c# introduce new concept is Indexer. It allows your class to be used just like an array. On the inside of a class, you manage a collection of values any way you want. This is very useful for some situation. Let as discuss something about Indexer.

• Indexer Concept is object act as an array.
• Indexer an object to be indexed in the same way as an array.
• Indexer modifier can be private, public, protected or internal.
• The return type can be any valid C# types.
• Indexers in C# must have at least one parameter. Else the compiler will generate a compilation error.

General Syntax of Indexers..................

[access-modifier] return-type this [Type of Indexer]
{    get{   }
     set {   }
}

Practical implementation with Indexers in C# .Net

using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

using System.Windows.Forms;

namespace IndexerConcept

{

public partial class Form1 : Form

{

public Form1()

{

InitializeComponent();

}

//create class which name is IntCollection

class IntCollection

{

private int[] arr = new int[100];

private int index = 0;

//decalre Indexer .................

public int this[int index]

{

get

{

return arr[index];

}

set

{

arr[index] = value;

}

}

}

//use above Indexer on Button_Click

private void btnAdd_Click(object sender, EventArgs e)

{

IntCollection obj = new IntCollection();

obj[0] = 12;

obj[5]=78;

int res = obj[0];

MessageBox.Show("Values of index 0 is=" + res);

int res1 = obj[5];

MessageBox.Show("Values of index 5 is=" + res1);

}

}

}

Result

Above Concept without using any Indexers (Using two different Method)

using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

using System.Windows.Forms;

namespace IndexerConcept

{

public partial class Form1 : Form

{

public Form1()

{

InitializeComponent();

}

//create class which name is IntCollection

class IntCollection

{

private int[] arr = new int[100];

private int index = 0;

//create metthod for add no with AddNo method

public void AddNo(int no)

{

arr[index] = no;

index++;

}

//create metthod for get no with index

public int GetNo(int index)

{

return arr[index];

}

}

//call above method on button_Click

private void btnAdd_Click(object sender, EventArgs e)

{

IntCollection obj = new IntCollection();

obj.AddNo(12);

obj.AddNo(78);

int res = obj.GetNo(0);

MessageBox.Show("Values of index 0 is=" + res);

int res1 = obj.GetNo(1);

MessageBox.Show("Values of index 0 is=" + res1);

}

}

}