呵呵，这个标题太拗口，和绕口令差不多了。我们都知道向一个方法传递值类型参数时，按值传递和按引用传递参数是不同的。按值传递时只是传递参数的一个副本，方法内对参数对改变并不会影响原来的值。而按引用传递实际是把参数的地址传递到方法中，方法内对参数对改变会影响原来的值。而当参数是引用类型时会发生什么情况呢？引用类型作为参数本身就是传递其引用地址，所以按值传递引用类型并不会传送该参数的副本。而按引用传递引用类型时是传递其引用地址的引用。换句话说，按值传递引用类型时，可以修改该参数内的成员，并会影响原来的引用类型。但是如果为该参数创建了一个新的实例，那么并不会影响原来的引用类型。而引用传递时为该参数创建一个新的实例会影响原来的引用类型。
class PassingRefByVal
{
static void Change(int[] pArray)
{
pArray[0] = 888; // This change affects the original element.
pArray = new int[5] {-3, -1, -2, -3, -4}; // This change is local.
System.Console.WriteLine("Inside the method, the first element is: {0}", pArray[0]);
}
static void Main()
{
int[] arr = {1, 4, 5};
System.Console.WriteLine("Inside Main, before calling the method, the first element is: {0}", arr [0]);
Change(arr);
System.Console.WriteLine("Inside Main, after calling the method, the first element is: {0}", arr [0]);
}
}
//output:
//Inside Main, before calling the method, the first element is: 1
//Inside the method, the first element is: -3
//Inside Main, after calling the method, the first element is: 888
class PassingRefByRef
{
static void Change(ref int[] pArray)
{
// Both of the following changes will affect the original variables:
pArray[0] = 888;
pArray = new int[5] {-3, -1, -2, -3, -4};
System.Console.WriteLine("Inside the method, the first element is: {0}", pArray[0]);
}
static void Main()
{
int[] arr = {1, 4, 5};
System.Console.WriteLine("Inside Main, before calling the method, the first element is: {0}", arr[0]);
Change(ref arr);
System.Console.WriteLine("Inside Main, after calling the method, the first element is: {0}", arr[0]);
}
}
//output:
//Inside Main, before calling the method, the first element is: 1
//Inside the method, the first element is: -3
//Inside Main, after calling the method, the first element is: -3
