Jagged array is an array of array it means jagged array is a collection of homogeneous arrays. An arrays inside the jagged array are of different length. As the jagged array contains the arrays therefore its collection of homogeneous reference type elements.

Syntax:
int [][]ar;

We can Declaration and initialization of jagged array in two way :

1. First Method

int [][]ar=new int[5][];
ar[0] = new int[3];
ar[1] = new int[5];
ar[2] = new int[2];
ar[3] = new int[4];
ar[4] = new int[6];

ar[0] = new int[] { 9, 5, 90 };
ar[1] = new int[] { 10, 20, 22, 40, 46 };
ar[2] = new int[] { 11, 56 };
ar[4] = new int[] { 1, 60, 2, 47, };
ar[6] = new int[] { 4, 5, 2, 4, 67, 34 };

2. Second Method

int[][] ar= new int[][]
{
new int[] { 9, 5, 90 },
new int[] { 10, 20, 22, 40, 46 },
new int[] { 11, 56 },
new int[] { 1, 60, 2, 47, }
new int[] { 4, 5, 2, 4, 67, 34 }
};

Below example illustrate the how to use a jagged array

using System;
namespace ArraySampleApplication
{
   class JaggedArrays
   {
      static void Main(string[] args)
      {
         int[][] arr = new int[][]{
                           new int[]{10,20,30,40},
                           new int[]{11,22,33,44},
                           new int[]{20,40,50,60},
                          };
         int i, j;
         for (i = 0; i < 3; i++)
         {
            for (j = 0; j < 4; j++)
            {
               Console.WriteLine("arr[{0}][{1}] = {2}", i, j, arr[i][j]);
            }
         }
         Console.ReadKey();
      }
   }
}

OUTPUT

arr[0][0]=10
arr[0][1]=20
arr[0][2]=30
arr[0][3]=40

arr[1][0]=11
arr[1][1]=22
arr[1][2]=33
arr[1][3]=44

arr[2][0]=20
arr[2][1]=40
arr[2][2]=50
arr[2][3]=60