将数组作为参数传递（C# 编程指南）

数组可作为实参传递给方法形参。 由于数组是引用类型，因此方法可以更改元素的值。

将一维数组作为参数传递

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可以将初始化的一维数组传递给方法。 例如，下面的语句将数组发送到 print 方法。

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

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

下面的代码显示 print 方法的部分实现。

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

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

您可以在一个步骤中初始化和传递新数组，如下面的示例所示。

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

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

示例

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说明

在下面的示例中，将初始化一个字符串数组并将其作为参数传递到字符串的 PrintArray 方法。 该方法显示数组的元素。 接下来，调用 ChangeArray 和 ChangeArrayElement 方法以演示通过值发送数组参数时不会阻止更改这些数组元素。

代码

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

将多维数组作为参数传递

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可采用与传递一维数组相同的方式将初始化的多维数组传递给方法。

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

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

下面的代码显示 print 方法的部分声明，该方法接受一个二维数组作为其参数。

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

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

您可以在一个步骤中初始化和传递新数组，如下面的示例所示。

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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说明

在下面的示例中，将初始化一个二维整数数组并将其传递到 Print2DArray 方法。该方法显示数组的元素。

代码

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    */