What are two-dimensional arrays in C#?

A two-dimensional array in C# is an array of arrays, where elements are arranged in rows and columns like a table or matrix. It stores data in a grid format with two indices: one for the row and one for the column.

Two-dimensional arrays are useful for representing tabular data, matrices, game boards, or any data structure that requires a grid-like organization.

Syntax

Following is the syntax for declaring a two-dimensional array −

datatype[,] arrayName = new datatype[rows, columns];

Following is the syntax for initializing a two-dimensional array with values −

int[,] arrayName = new int[2,3] {
   {1, 2, 3},
   {4, 5, 6}
};

Using Two-Dimensional Arrays

Example 1: Basic Declaration and Access

This example shows how to declare, initialize, and access elements in a two-dimensional array −

using System;

class Program {
   static void Main(string[] args) {
      // Declare and initialize a 2D array
      int[,] numbers = new int[2, 3] {
         {1, 2, 3},
         {4, 5, 6}
      };

      // Access and display individual elements
      Console.WriteLine("Element at [0,0]: " + numbers[0,0]);
      Console.WriteLine("Element at [1,2]: " + numbers[1,2]);

      // Get dimensions
      Console.WriteLine("Rows: " + numbers.GetLength(0));
      Console.WriteLine("Columns: " + numbers.GetLength(1));
   }
}

The output of the above code is −

Element at [0,0]: 1
Element at [1,2]: 6
Rows: 2
Columns: 3

Traversing Two-Dimensional Arrays

Example 2: Using Nested Loops

This example demonstrates how to traverse through all elements of a two-dimensional array using nested loops −

using System;

class Program {
   static void Main(string[] args) {
      // Create a 3x2 array
      int[,] matrix = new int[3, 2] {{0,0}, {1,2}, {2,4}};

      Console.WriteLine("Matrix elements:");
      // Traverse using nested for loops
      for (int i = 0; i < matrix.GetLength(0); i++) {
         for (int j = 0; j < matrix.GetLength(1); j++) {
            Console.WriteLine("matrix[{0},{1}] = {2}", i, j, matrix[i,j]);
         }
      }
   }
}

The output of the above code is −

Matrix elements:
matrix[0,0] = 0
matrix[0,1] = 0
matrix[1,0] = 1
matrix[1,1] = 2
matrix[2,0] = 2
matrix[2,1] = 4

Example 3: Matrix Operations

This example shows practical usage of two-dimensional arrays for matrix operations −

using System;

class Program {
   static void Main(string[] args) {
      // Create two 2x2 matrices
      int[,] matrixA = {{1, 2}, {3, 4}};
      int[,] matrixB = {{5, 6}, {7, 8}};
      int[,] result = new int[2, 2];

      // Add matrices
      for (int i = 0; i < 2; i++) {
         for (int j = 0; j < 2; j++) {
            result[i, j] = matrixA[i, j] + matrixB[i, j];
         }
      }

      // Display result
      Console.WriteLine("Matrix Addition Result:");
      for (int i = 0; i < 2; i++) {
         for (int j = 0; j < 2; j++) {
            Console.Write(result[i, j] + " ");
         }
         Console.WriteLine();
      }
   }
}

The output of the above code is −

Matrix Addition Result:
6 8 
10 12

Common Use Cases

• Mathematical matrices − For linear algebra operations and calculations

• Game boards − Chess, tic-tac-toe, or other grid-based games

• Image processing − Storing pixel data in rows and columns

• Tabular data − Representing spreadsheet-like data structures

Conclusion

Two-dimensional arrays in C# provide an efficient way to store and manipulate grid-like data structures. They use row and column indices for element access and are ideal for mathematical computations, game development, and any scenario requiring tabular data organization.