要改变参数的值，可以用引用传值方式(使用ref关键字)
/*
Example5_7.cs illustrates passing parameters by reference
*/
// declare the Swapper class
public class Swapper
{
// the Swap() method swaps parameters passed by reference
public void Swap(ref int x, ref int y)
{
// display the initial values
System.Console.WriteLine("In Swap(): initial x = " + x +
", y = " + y);
// swap x and y
int temp = x;
x = y;
y = temp;
// display the final values
System.Console.WriteLine("In Swap(): final x = " + x +
", y = " + y);
}
}
class Example5_7
{
public static void Main()
{
// declare x and y (the variables whose values
// are to be swapped)
int x = 2;
int y = 5;
// display the initial values
System.Console.WriteLine("In Main(): initial x = " + x +
", y = " + y);
// create a Swapper object
Swapper mySwapper = new Swapper();
// swap the values, passing a reference to the Swap() method
mySwapper.Swap(ref x, ref y);
// display the final values
System.Console.WriteLine("In Main(): final x = " + x +
", y = " + y);
string i = System.Console.ReadLine();
}
}