C# 使用ref和out关键字

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

namespace ConsoleApplication1
{
    class Program
    {
        static void refMethod(ref string s)
        {
            s = "wangyuanfeng";
        }

        static void outMethod(out int i,out string str1,out string str2)
        {
            i = 44;
            str1 = "I‘ve been returned";
            str2 = null;
        }
                
        static void Main(string[] args)
        {
            string str = "old";
            int value = new int();
            string str1 = "old1";
            string str2 = "old2";
            
            Console.WriteLine("use ref:");
            Console.WriteLine("refMethod()before:\n str = {0}", str);
            refMethod(ref str);
            Console.WriteLine("refMethod() after :\n str = {0}", str);
            
            Console.WriteLine("use out:");
            Console.WriteLine("outMethod() before:\n nvalue = {0};nstr1 = {1},nstr2 = {2}", value, str1, str2);
            outMethod(out value, out str1, out str2);
            Console.WriteLine("outMethod() after:\n nvalue = {0},nstr1 = {1},nstr2 = {2}", value, str1, str2);

            Console.Read();
        }
    }
}