C# Multidimensional Arrays: 2D Arrays Explained with Code Examples

C# Multidimensional Arrays

In this tutorial, we’ll explore C#’s multidimensional arrays, focusing on two‑dimensional examples with clear code snippets.

Before diving into multidimensional arrays, review C#’s single‑dimensional arrays.

In a multidimensional array, each element is itself an array. For example,

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

Here, x is a two‑dimensional array containing the rows {1, 2, 3} and {3, 4, 5}. Each row is an array of three elements.

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Two‑Dimensional Array in C#

A two‑dimensional array is essentially a table of rows and columns. The array’s elements are single‑dimensional arrays.

In the image, the rows {1, 2, 3} and {3, 4, 5} represent the two rows of the 2D array.

1. Declaration

Declare a 2D array like this:

int[ ] x = new int [2, 3];

Here, x can hold 2 rows and 3 columns—6 values in total.

Note: The single comma between brackets ([ ]) indicates a two‑dimensional array.

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2. Initialization

You can initialize the array at declaration:

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

Or specify size and values simultaneously:

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

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3. Accessing Elements

Use zero‑based indices: x[row, column]. Examples:

// 2D array
int[ ] x = { { 1, 2 ,3}, { 3, 4, 5 } };

// first element of first row
x[0, 0];  // 1

// third element of second row
x[1, 2];  // 5

// third element of first row
x[0, 2];  // 3

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Example: C# 2D Array

using System;

namespace MultiDArray {
  class Program {
    static void Main(string[] args) {
       
        //initializing 2D array
       int[ ] numbers = {{2, 3}, {4, 5}};
       
        // access first element from the first row
       Console.WriteLine("Element at index [0, 0] : "+numbers[0, 0]);
       
        // access first element from second row
       Console.WriteLine("Element at index [1, 0] : "+numbers[1, 0]);
    }
  }
}

Output

Element at index [0, 0] : 2
Element at index [1, 0] : 4

In this example, numbers has rows {2, 3} and {4, 5}. We print values using the indices shown.

• numbers[0, 0] – first element of first row (2)
• numbers[1, 0] – first element of second row (4)

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Changing Elements

Assign a new value to an index to modify the array:

using System;

namespace MultiDArray {
  class Program {
    static void Main(string[] args) {

    int[ ] numbers = {{2, 3}, {4, 5}};
     
     // old element
    Console.WriteLine("Old element at index [0, 0] : "+numbers[0, 0]);
     
      // assigning new value
    numbers[0, 0] = 222;
     
      // new element
    Console.WriteLine("New element at index [0, 0] : "+numbers[0, 0]);
    }
  }
}

Output

Old element at index [0, 0] : 2
New element at index [0, 0] : 222

Here, the value at [0, 0] changes from 2 to 222.

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Iterating with Nested Loops

using System;

namespace MultiDArray {
  class Program  {
    static void Main(string[] args)  {

      int[ ] numbers = { {2, 3, 9}, {4, 5, 9} };
     
      for(int i = 0; i < numbers.GetLength(0); i++)  { 
        Console.Write("Row "+ i+": ");

        for(int j = 0; j < numbers.GetLength(1); j++)  { 
          Console.Write(numbers[i, j]+" ");
 
        }
        Console.WriteLine(); 
 
      }  
    }
  }
}

Output

Row 0: 2 3 9
Row 1: 4 5 9

The outer loop iterates over rows (GetLength(0)), the inner loop over columns (GetLength(1)).

Note: A three‑dimensional array contains multiple 2D arrays:

int[ , ] numbers = { { { 1, 3, 5 }, { 2, 4, 6 } },
                                 { { 2, 4, 9 }, { 5, 7, 11 } } };

Here, [ , ] (two commas) denotes a 3D array.