Jagged Arrays (C# Programming )

Jagged Arrays (C# Programming )

A jagged array is an array whose elements are arrays. The elements of a jagged array can be of different dimensions and sizes. A jagged array is sometimes called an "array of arrays." The following examples show how to declare, initialize, and access jagged arrays.

The following is a declaration of a single-dimensional array that has three elements, each of which is a single-dimensional array of integers:

int[][] jaggedArray = new int[3][];

Before you can use jaggedArray, its elements must be initialized. You can initialize the elements like this:

jaggedArray[0] = new int[5];

jaggedArray[1] = new int[4];

jaggedArray[2] = new int[2];

Each of the elements is a single-dimensional array of integers. The first element is an array of 5 integers, the second is an array of 4 integers, and the third is an array of 2 integers.

It is also possible to use initializers to fill the array elements with values, in which case you do not need the array size. For example:

jaggedArray[0] = new int[] { 1, 3, 5, 7, 9 };

jaggedArray[1] = new int[] { 0, 2, 4, 6 };

jaggedArray[2] = new int[] { 11, 22 };

You can also initialize the array upon declaration like this:

    int[][] jaggedArray2 = new int[][]

{

    new int[] {1,3,5,7,9},

    new int[] {0,2,4,6},

    new int[] {11,22}

};

You can use the following shorthand form. Notice that you cannot omit the new operator from the elements initialization because there is no default initialization for the elements:

    int[][] jaggedArray3 =

{

    new int[] {1,3,5,7,9},

    new int[] {0,2,4,6},

    new int[] {11,22}

};

A jagged array is an array of arrays, and therefore its elements are reference types and are initialized to null.

You can access individual array elements like these examples:

// Assign 77 to the second element ([1]) of the first array ([0]):

jaggedArray3[0][1] = 77;

// Assign 88 to the second element ([1]) of the third array ([2]):

jaggedArray3[2][1] = 88;

It is possible to mix jagged and multidimensional arrays. The following is a declaration and initialization of a single-dimensional jagged array that contains two-dimensional array elements of different sizes:

int[][,] jaggedArray4 = new int[3][,]

{

    new int[,] { {1,3}, {5,7} },

    new int[,] { {0,2}, {4,6}, {8,10} },

    new int[,] { {11,22}, {99,88}, {0,9} }

};

You can access individual elements as shown in this example, which displays the value of the element [1,0] of the first array (value 5):

System.Console.Write("{0}", jaggedArray4[0][1, 0]);

The method Length returns the number of arrays contained in the jagged array. For example, assuming you have declared the previous array, this line:

System.Console.WriteLine(jaggedArray4.Length);

will return a value of 3.

Example

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This example builds an array whose elements are themselves arrays. Each one of the array elements has a different size.

class ArrayTest

{

    static void Main()

    {

        // Declare the array of two elements:

        int[][] arr = new int[2][];

        // Initialize the elements:

        arr[0] = new int[5] { 1, 3, 5, 7, 9 };

        arr[1] = new int[4] { 2, 4, 6, 8 };

        // Display the array elements:

        for (int i = 0; i < arr.Length; i++)

        {

            System.Console.Write("Element({0}): ", i);

            for (int j = 0; j < arr[i].Length; j++)

            {

                System.Console.Write("{0}{1}", arr[i][j], j == (arr[i].Length - 1) ? "" : " ");

            }

            System.Console.WriteLine();

        }

    }

}

Output

---

Element(0): 1 3 5 7 9

Element(1): 2 4 6 8