Passing Arrays as Arguments (C# Programming Guide)

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

Passing Single-Dimensional Arrays As Arguments

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 });

Example

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

Passing Multidimensional Arrays As Arguments

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 } });

Example

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
*/

See Also

Concepts

C# Programming Guide

Reference

Arrays (C# Programming Guide)

Single-Dimensional Arrays (C# Programming Guide)

Multidimensional Arrays (C# Programming Guide)

Jagged Arrays (C# Programming Guide)

Change History

Date	History	Reason
July 2009	Improved the two-dimensional example.	Customer feedback.