C#--索引

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

namespace ConsoleApplication2
{
   public class Employee
    {
       public string FirstName;
       public string Lastname;
       public string CityOfBirth;

       /// <summary>
       /// 创建索引
       /// </summary>
       /// <param name="index"></param>
       /// <returns></returns>
       public string this[int index]
       {
           set 
           {
               switch (index)
               {
                   case 0: FirstName = value; break;
                   case 1: Lastname = value; break;
                   case 2: CityOfBirth = value; break;
                   default:
                       throw new ArgumentOutOfRangeException("index");
               }
           }
           get 
           
           {
               switch (index)
               {
                   case 0: return FirstName;
                   case 1: return Lastname;
                   case 2: return CityOfBirth;
                   default:
                       throw new ArgumentOutOfRangeException("index");
               }
           }
       }
    }
}