(C#基础) ref 和out练习

    对于C#中这两个关键字的用法，常常混淆，有点不清楚，今天又一次看到。遂把它们都记录下来，希望能有所用。这些都是他人写的，我只是搬过来一次，加深印象。

   代码

  

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

namespace dazilianxi.wenjian
{
    public class MoTes:IEnumerable<SanWei>
    {
        private readonly List<SanWei> _motes;
        public MoTes()
        {
            _motes = new List<SanWei>();
        }

        public void Add(double xiong,double yao,double tun)
        {
            _motes.Add(new SanWei(xiong,yao,tun));
        }
        #region IEnumerable<SanWei> 成员

        public IEnumerator<SanWei> GetEnumerator()
        {
            //throw new NotImplementedException();

            return _motes.GetEnumerator();
        }

        #endregion

        #region IEnumerable 成员

        System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator()
        {
           // throw new NotImplementedException();
            return GetEnumerator();
        }

        #endregion
    }
    //一定要灵活使用
    public struct SanWei
    {
        public readonly double _Xiong;
        public readonly double _Yao;
        public readonly double _Tun;
        public SanWei(double xiong,double yao,double tun)
        {
            this._Xiong = xiong;
            this._Yao = yao;
            this._Tun = tun;
        }
    }

    public class Pet 
    {
        public int Age { get; set; }
        public static void ChageAge(Pet p)
        {
            p.Age = 10;
        }

        public static void ChangePet(ref Pet p)
        {
            p = new Pet()
            {
                Age=20
            };
        }
    }

    public class Player
    {
        public int Id { get; set; }
        public string Name{get;set;}
        public string Position { get; set; }
        public bool IsbestPlayer { get; set; }
    }

    public class Team
    {
        public Team()
        {
            listPlay = new List<Player>();
        }
        public int Id { get; set; }
        public string Name { get; set; }
        public int ScoreCount { get; set; }
        public List<Player> listPlay { get; set; }

        /*
          out和ref：
            ● 相同的地方在于：传递的引用
            ● 不同之处在于：ref在使用之前需要赋上初值，out可以赋初值也可以不赋
         */
        //out为了在方法内改变值，然后在外面调用，ref 是作为一个判断条件，在方法里用，也可以发生改变
        public static  void WhoWinWorldCup(Team a, Team b, out string bestPlayer) 
        {
            if(a.ScoreCount>b.ScoreCount)
            {
                Console.WriteLine("恭喜{0}对，赢得了这次比赛",a.Name);
            }
            else
            {
                 Console.WriteLine("恭喜{0}对，赢得了这次比赛",a.Name);
            }
            bestPlayer=LookForBestPlayer(a,b);
        }

        public static string LookForBestPlayer(Team a ,Team b)
        {
            string result = string.Empty;
            //把Team b的球员合并到Team a中去
            a.listPlay.AddRange(b.listPlay);
            foreach( var plays in a.listPlay)
            {
                if(plays.IsbestPlayer==false)
                {
                    continue;
                }
                else
                {
                    result = plays.Name;
                    break;
                }
            }
            return result;
        }
    }
}

main 中

 /* var list = new MoTes()
            {
                {79, 60, 89},
                {82, 63, 90}
            };
            foreach (var item in list)
            {
                Console.WriteLine("胸围：{0},腰围：{1}，臀围：{2}", item._Xiong, item._Yao, item._Tun);
            }
            */
            /*
            //ref 使用前必须赋值，out不需要
            //out必须在方法里赋值，外面赋值不起作用，ref 在里面可以发生变化 
            //相同点都是取变化值灵活调用

            Pet p = new Pet() { Age = 5 };
            Console.WriteLine("初始年龄是：{0}", p.Age);
            Pet.ChageAge(p);
            Console.WriteLine("改变pet的属性值后，年龄是：{0}", p.Age);
            Pet.ChangePet(ref  p);
            Console.WriteLine("改变pet引用地址后，年龄是：{0}", p.Age);
            Console.ReadKey();*/

            Console.WriteLine("央视足球解说员贺炜：欢迎大家来到本届世界杯的决赛现场~~");
            Console.WriteLine("央视足球解说员贺炜：决赛的2支队伍是：");

            Team brazil = new Team()
            {
                Id = 1,
                Name = "巴西队",
                listPlay = new List<Player>()
                {
                    new Player(){Id = 1, Name = "内马尔", Position = "前锋"},
                    new Player(){Id = 2, Name = "阿尔维斯", Position = "后卫"}
                }
            };

            Team germany = new Team()
            {
                Id = 2,
                Name = "德国队",
                listPlay = new List<Player>()
                {
                    new Player(){Id = 3, Name = "齐勒", Position = "前锋"},
                    new Player(){Id = 4, Name = "拉姆", Position = "后卫"}
                }
            };

            Console.WriteLine("来自南美的{0}主场迎战来自欧洲的劲旅{1}", brazil.Name, germany.Name);

            Console.WriteLine("在比赛的89分钟，德国队前锋齐勒禁区外抽射死角，锁定胜局~~");
            germany.listPlay[0].IsbestPlayer = true;
            germany.ScoreCount = 1;
            brazil.ScoreCount = 0;

            string best = string.Empty;
           Team.WhoWinWorldCup(brazil, germany, out best);
            Console.WriteLine("本场比赛的最佳球员是：{0}", best);
            Console.WriteLine();
            Console.WriteLine("央视足球解说员贺炜：这是牵动人心的90分钟。在这场比赛之后，总有一支球迷热爱的球队要离开，而这场比赛本身，将成为我们记忆中的永恒财富。等我们老去的时候，在壁炉旁抱着自己的孙子，一定会跟他们讲起2014年，讲起今晚的巴德大战。");
            Console.ReadKey();

参考：

http://www.cnblogs.com/darrenji/p/3821313.html

http://www.cnblogs.com/darrenji/p/3822000.html