C# | Multidimensional Indexers

Prerequisite: Indexers in C#

The multi-dimensional indexer is almost similar to multidimensional arrays. For the efficient content-based retrieval of data, multidimensional indexers are used. To create multi-dimensional indexer you have to pass at least two parameters in the argument list of indexer declaration. To access a single element of a multi-dimensional indexer, use integer subscripts. Each subscript indexes a dimension like the first indexes the row dimension, the second indexes the column dimension and so on.

Example 1: Using get and set accessor

// C# program to illustrate the
// Multidimensional Indexers
using System;


class GFG {

    // reference to underlying 2D array
    int[, ] data = new int[5, 5];


    // declaring Multidimensional Indexer
    public int this[int index1, int index2]
    {
        // get accessor
        get
        {

             // it returns the values which
            // read the indexes
            return data[index1, index2];

        }

        // set accessor
        set
        {

            // write the values in 'data'
            // using value keyword
            data[index1, index2] = value;

        }
    }
}

// Driver Class
class Geeks {


    // Main Method
    public static void Main(String []args)
    {

        // creating the instance of
        // Class GFG as "index"
        GFG index = new GFG();


        // assign the values accordingly to
        // the indexes of the array
        // 1st row
        index[0, 0] = 1;
        index[0, 1] = 2;
        index[0, 2] = 3;

        // 2nd row
        index[1, 0] = 4;
        index[1, 1] = 5;
        index[1, 2] = 6;

        // 3rd row
        index[2, 0] = 7;
        index[2, 1] = 8;
        index[2, 2] = 9;

        // displaying the values
        Console.WriteLine("{0}\t{1}\t{2}\n{3}\t{4}\t{5}\n{6}\t{7}\t{8}",
                                  index[0, 0], index[0, 1], index[0, 2],
                                  index[1, 0], index[1, 1], index[1, 2],
                                  index[2, 0], index[2, 1], index[2, 2]);

    }
}

Output:

1    2    3
4    5    6
7    8    9

Example 2: Without using the “set” accessor i.e only using Read-Only Property

// C# program to illustrate the Multidimensional
// Indexer without using set accessor
using System;

class GFG {

    // default constructor
    public GFG() {}

    // Multidimensional Indexer
    public int this[int i1, int i2]
    {

        // get accessor
        get
        {

            // read only properties
            return (i1 + i2);
        }

        // No set accessor used
    }

// Main Method
public static void Main(String []args)
{

    // creating object of class
    // "GFG" as "index"
    GFG index = new GFG();

    // displaying the values
    for (int i = 0; i <= 2; i++) {

        for (int j = 1; j <= 3; j++)
        {
            Console.Write(index[i, j] + "\t");
        }

        Console.WriteLine();
    }
}
}

Output:

1    2    3    
2    3    4    
3    4    5