C# 索引器使用总结

    /// <summary>
    /// 最简单的索引器
    /// </summary>
    public class IDXer
    {
        private string[] name=new string[10];

        //索引器必须以this关键字定义，其实这个this就是类实例化之后的对象
        public string this[int index]
        {
            get 
            {
                return name[index];
            }
            set
            {
                name[index] = value;
            }
        }  
    }
        
    public class Program
    {
        static void Main(string[] args)
        {
            //最简单索引器的使用           
            IDXer indexer = new IDXer();
            //“=”号右边对索引器赋值，其实就是调用其set方法
            indexer[0] = "张三";
            indexer[1] = "李四";
            //输出索引器的值，其实就是调用其get方法
            Console.WriteLine(indexer[0]);
            Console.WriteLine(indexer[1]);
            Console.ReadKey();
        }
    }

    //以字符串为下标的索引器
    public class IDXer2
    {
        private Hashtable name = new Hashtable();

        //以字符串为下标的索引器
        public string this[string index]
        {
            get
            {
                return name[index].ToString();
            }
            set
            {
                name.Add(index, value);
            }
        } 
    }

    public class Program
    {
        static void Main(string[] args)
        {
            //以字符串为下标的索引器
            IDXer2 indexer2 = new IDXer2();
            indexer2["A01"] = "张三";
            indexer2["A02"] = "李四";
            Console.WriteLine(indexer2["A01"]);
            Console.WriteLine(indexer2["A02"]);
            Console.ReadKey();
        }
  }

    /// <summary>
    /// 成绩类
    /// </summary>
    public class Scores
    {
        /// <summary>
        /// 学生姓名
        /// </summary>
        public string StuName { get; set; }

        /// <summary>
        /// 课程ID
        /// </summary>
        public int CourseId { get; set; }

        /// <summary>
        /// 分数
        /// </summary>
        public int Score { get; set; }
       
    }

    /// <summary>
    /// 查找成绩类（索引器）
    /// </summary>
    public class FindScore
    {
        private List<Scores> listScores;

        public FindScore()
        {
            listScores = new List<Scores>();
        }

        //索引器 通过名字&课程编号查找和保存成绩
        public int this[string stuName, int courseId]
        {
            get
            {
                Scores s = listScores.Find(x => x.StuName == stuName && x.CourseId == courseId);
                if (s != null)
                {
                    return s.Score;
                }
                else
                {
                    return -1;
                }
            }
            set
            {
                listScores.Add(new Scores() { StuName = stuName, CourseId = courseId, Score = value });
            }
        }

        //索引器重载，根据名字查找所有成绩
        public List<Scores> this[string stuName]
        {
            get
            {
                List<Scores> tempList = listScores.FindAll(x => x.StuName == stuName);
                return tempList;
            }
        }
    }

   static void Main(string[] args)
   {
       //多参数索引器和索引器重载          
       FindScore fScore = new FindScore();
       fScore["张三", 1] = 98;
       fScore["张三", 2] = 100;
       fScore["张三", 3] = 95;
       fScore["李四", 1] = 96;
       //查找 张三 课程编号2 的成绩
       Console.WriteLine("李四 课程编号2 成绩为:" + fScore["李四", 1]);
       //查找所有张三的成绩
       List<Scores> listScores = fScore["张三"];
       if (listScores.Count > 0)
       {
          foreach (Scores s in listScores)
          {
             Console.WriteLine(string.Format("张三 课程编号{0} 成绩为:{1}", s.CourseId, s.Score));
          }
       }
       else
       {
           Console.WriteLine("无该学生成绩单");
       }
       Console.ReadKey();
   }