當value type, reference type 遇上 call by value, call by reference

using System;
using System.Text;
using System.Collections.Generic;

public class Example2
{
    static void testPar(ref String p1, String p2, StringBuilder p3)
    {
        p1 = "hello!!";
        p2 = "hello!!"; //p2 += "hello!!";
        p3 = new StringBuilder("YoYo");//.Append("hello!!");
    }
    static void Main(string[] args)
    {
        String s1 = "A";
        String s2 = "B";
        StringBuilder s3 = new StringBuilder("C");
        testPar(ref s1, s2, s3);
        Console.Write("{0}\n  {1}\n  {2}\n", s1, s2, s3);
        Console.ReadLine();

    }
}