Question

C#中数组作为参数传递的问题，非常疑惑，恳请各位大神指点，帮忙看下这个MSDN上的例程，谢谢了！

一个MSDN上C#中数组作为参数传递的例程：
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);
}
}

程序的输出是:
// 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

这就奇怪了，两个函数ChangeArray()和ChangeArrayElements()都是传递的同一个数组作为参数，也都是在各自的函数内部对传递进来的数组参数作更改，但为什么ChangeArray()没能改变weekDays数组的值，而ChangeArrayElements()却改变了呢？实在不得其解，恳求指点！谢谢！

Answer 1

C语言学过吧， ChangeArray函数中的arr变量就相当于C里的调用函数里的动态变量，当函数结束时就释放了，而ChangeArrayElements函数是对数组元素（string型）赋值，所以改了。回答的不好别笑啊，这种事有时候只可意会不可言传，麻烦你把上面这些代码的链接发给我，前段时间看到过，现在找不到了

Answer 2

ChangeArrayElements 是改变了某个元素的值。

ChangeArray 只是反转了，改变了元素的顺序

追问

是这样没错啊，但请问，ChangeArrayElements()和ChangeArray()都有对参数数组赋值的语句
：
arr[0] = "Sat";
和

arr = (arr.Reverse()).ToArray();
这不是一回事吗？都是对参数数组进行操作啊，为什么结果不一样呢？感谢！

追答

ChangeArray() 方法中

这句不报错吗？？
arr = (arr.Reverse()).ToArray();

追问

不报错啊…我运行过的…请问是怎么回事？