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Passing Arrays as Arguments (C# Programming Guide)

Updated: July 2009

Arrays can be passed as arguments to method parameters. Because arrays are reference types, the method can change the value of the elements.

You can pass an initialized single-dimensional array to a method. For example, the following statement sends an array to a print method.

int[] theArray = { 1, 3, 5, 7, 9 };
PrintArray(theArray);

The following code shows a partial implementation of the print method.

void PrintArray(int[] arr)
{
    // Method code.
}

You can initialize and pass a new array in one step, as is shown in the following example.

PrintArray(new int[] { 1, 3, 5, 7, 9 });

Description

In the following example, an array of strings is initialized and passed as an argument to a PrintArray method for strings. The method displays the elements of the array.

Code

class ArrayClass
{
    static void PrintArray(string[] arr)
    {
        for (int i = 0; i < arr.Length; i++)
        {
            System.Console.Write(arr[i] + "{0}", i < arr.Length - 1 ? " " : "");
        }
        System.Console.WriteLine();
    }

    static void Main()
    {
        // Declare and initialize an array. 
        string[] weekDays = { "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat" };

        // Pass the array as an argument to PrintArray.
        PrintArray(weekDays);
    }
}
// Output: Sun Mon Tue Wed Thu Fri Sat

You pass an initialized multidimensional array to a method in the same way that you pass a one-dimensional array.

int[,] theArray = { { 1, 2 }, { 2, 3 }, { 3, 4 } };
Print2DArray(theArray);

The following code shows a partial declaration of a print method that accepts a two-dimensional array as its argument.

void Print2DArray(int[,] arr)
{
    // Method code.
}

You can initialize and pass a new array in one step, as is shown in the following example.

Print2DArray(new int[,] { { 1, 2 }, { 3, 4 }, { 5, 6 }, { 7, 8 } });

Description

In the following example, a two-dimensional array of integers is initialized and passed to the Print2DArray method. The method displays the elements of the array.

Code

class ArrayClass2D
{
    static void Print2DArray(int[,] arr)
    {
        // Display the array elements. 
        for (int i = 0; i < arr.GetLength(0); i++)
        {
            for (int j = 0; j < arr.GetLength(1); j++)
            {
                System.Console.WriteLine("Element({0},{1})={2}", i, j, arr[i, j]);
            }
        }
    }
    static void Main()
    {
        // Pass the array as an argument.
        Print2DArray(new int[,] { { 1, 2 }, { 3, 4 }, { 5, 6 }, { 7, 8 } });

        // Keep the console window open in debug mode.
        System.Console.WriteLine("Press any key to exit.");
        System.Console.ReadKey();
    }
}
/* Output:
    Element(0,0)=1
    Element(0,1)=2
    Element(1,0)=3
    Element(1,1)=4
    Element(2,0)=5
    Element(2,1)=6
    Element(3,0)=7
    Element(3,1)=8
*/

Date

History

Reason

July 2009

Improved the two-dimensional example.

Customer feedback.

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