將數組做爲參數傳遞（C# 編程指南）

數組可做爲實參傳遞給方法形參。 因爲數組是引用類型，所以方法能夠更改元素的值。

將一維數組做爲參數傳遞

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能夠將初始化的一維數組傳遞給方法。 例如，下面的語句將數組發送到 print 方法。

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

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

下面的代碼顯示 print 方法的部分實現。

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

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

您能夠在一個步驟中初始化和傳遞新數組，以下面的示例所示。

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

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

示例

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說明

在下面的示例中，將初始化一個字符串數組並將其做爲參數傳遞到字符串的 PrintArray 方法。 該方法顯示數組的元素。 接下來，調用 ChangeArray 和 ChangeArrayElement 方法以演示經過值發送數組參數時不會阻止更改這些數組元素。

代碼

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 ChangeArray(string[] arr)
    {
        // The following attempt to reverse the array does not persist when
        // the method returns, because arr is a value parameter.
        arr = (arr.Reverse()).ToArray();
        // The following statement displays Sat as the first element in the array.
        System.Console.WriteLine("arr[0] is {0} in ChangeArray.", arr[0]);
    }

    static void ChangeArrayElements(string[] arr)
    {
        // The following assignments change the value of individual array 
        // elements. 
        arr[0] = "Sat";
        arr[1] = "Fri";
        arr[2] = "Thu";
        // The following statement again displays Sat as the first element
        // in the array arr, inside the called method.
        System.Console.WriteLine("arr[0] is {0} in ChangeArrayElements.", arr[0]);
    }

    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);

        // ChangeArray tries to change the array by assigning something new
        // to the array in the method. 
        ChangeArray(weekDays);

        // Print the array again, to verify that it has not been changed.
        System.Console.WriteLine("Array weekDays after the call to ChangeArray:");
        PrintArray(weekDays);
        System.Console.WriteLine();

        // ChangeArrayElements assigns new values to individual array
        // elements.
        ChangeArrayElements(weekDays);

        // The changes to individual elements persist after the method returns.
        // Print the array, to verify that it has been changed.
        System.Console.WriteLine("Array weekDays after the call to ChangeArrayElements:");
        PrintArray(weekDays);
    }
}
// Output: 
// Sun Mon Tue Wed Thu Fri Sat
// arr[0] is Sat in ChangeArray.
// Array weekDays after the call to ChangeArray:
// Sun Mon Tue Wed Thu Fri Sat
// 
// arr[0] is Sat in ChangeArrayElements.
// Array weekDays after the call to ChangeArrayElements:
// Sat Fri Thu Wed Thu Fri Sat

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 ChangeArray(string[] arr)
    {
        // The following attempt to reverse the array does not persist when
        // the method returns, because arr is a value parameter.
        arr = (arr.Reverse()).ToArray();
        // The following statement displays Sat as the first element in the array.
        System.Console.WriteLine("arr[0] is {0} in ChangeArray.", arr[0]);
    }

    static void ChangeArrayElements(string[] arr)
    {
        // The following assignments change the value of individual array 
        // elements. 
        arr[0] = "Sat";
        arr[1] = "Fri";
        arr[2] = "Thu";
        // The following statement again displays Sat as the first element
        // in the array arr, inside the called method.
        System.Console.WriteLine("arr[0] is {0} in ChangeArrayElements.", arr[0]);
    }

    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);

        // ChangeArray tries to change the array by assigning something new
        // to the array in the method. 
        ChangeArray(weekDays);

        // Print the array again, to verify that it has not been changed.
        System.Console.WriteLine("Array weekDays after the call to ChangeArray:");
        PrintArray(weekDays);
        System.Console.WriteLine();

        // ChangeArrayElements assigns new values to individual array
        // elements.
        ChangeArrayElements(weekDays);

        // The changes to individual elements persist after the method returns.
        // Print the array, to verify that it has been changed.
        System.Console.WriteLine("Array weekDays after the call to ChangeArrayElements:");
        PrintArray(weekDays);
    }
}
// Output: 
// Sun Mon Tue Wed Thu Fri Sat
// arr[0] is Sat in ChangeArray.
// Array weekDays after the call to ChangeArray:
// Sun Mon Tue Wed Thu Fri Sat
// 
// arr[0] is Sat in ChangeArrayElements.
// Array weekDays after the call to ChangeArrayElements:
// Sat Fri Thu Wed Thu Fri Sat

將多維數組做爲參數傳遞

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可採用與傳遞一維數組相同的方式將初始化的多維數組傳遞給方法。

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

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

下面的代碼顯示 print 方法的部分聲明，該方法接受一個二維數組做爲其參數。

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

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

您能夠在一個步驟中初始化和傳遞新數組，以下面的示例所示。

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

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

示例

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說明

在下面的示例中，將初始化一個二維整數數組並將其傳遞到 Print2DArray 方法。 該方法顯示數組的元素。

代碼

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 */