C# Multidimensional Array

Before we learn about the multidimensional arrays, make sure to know about the single-dimensional array in C#.

In a multidimensional array, each element of the array is also an array. For example,

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

Here, x is a multidimensional array which has two elements: {1, 2, 3} and {3, 4, 5}. And, each element of the array is also an array with 3 elements.

Two-dimensional array in C#

A two-dimensional array consists of single-dimensional arrays as its elements. It can be represented as a table with a specific number of rows and columns.

Here, rows {1, 2, 3} and {3, 4, 5} are elements of a 2D array.

1. Two-Dimensional Array Declaration

Here's how we declare a 2D array in C#.

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

Here, x is a two-dimensional array with 2 elements. And, each element is also an array with 3 elements.

So, all together the array can store 6 elements (2 * 3).

Note: The single comma [ , ] represents the array is 2 dimensional.

2. Two-Dimensional Array initialization

In C#, we can initialize an array during the declaration. For example,

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

Here, x is a 2D array with two elements {1, 2, 3} and {3, 4, 5}. We can see that each element of the array is also an array.

We can also specify the number of rows and columns during the initialization. For example,

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

3. Access Elements from 2D Array

We use the index number to access elements of a 2D array. For example,

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

// access first element from first row
x[0, 0];  // returns 1

// access third element from second row
x[1, 2];  // returns 5

// access third element from first row
x[0, 2];  // returns 3

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 the above example, we have created a 2D array named numbers with rows {2, 3} and {4, 5}.

Here, we are using the index numbers to access elements of the 2D array.

• numbers[0, 0] - access the first element from the first row (2)
• numbers[1, 0] - access the first element from the second row (4)

Change Array Elements

We can also change the elements of a two-dimensional array. To change the element, we simply assign a new value to that particular index. For example,

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

In the above example, the initial value at index [0, 0] is 2. Notice the line,

// assigning new value
numbers[0, 0] = 222;

Here, we are assigning a new value 222 at index [0, 0]. Now, the value at index [0, 0] is changed from 2 to 222.

Iterating C# Array using Loop

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

In the above example, we have used a nested for loop to iterate through the elements of a 2D array. Here,

• numbers.GetLength(0) - gives the number of rows in a 2D array
• numbers.GetLength(1) - gives the number of elements in the row

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