引用传递参数

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();
    }

}