public class PeopleCollection : IEnumerable
{
       private ArrayList arPeople= new ArrayList();
       // 类的自定义索引器
       public Person this [int index]   // 除了多个this关键字外，和属性声明很相似
      {
             get{ return (Person)arPeople[index];}
             set{ arPeople.Insert(index,value);} // 使用ArrayList的Insert()方法
      }
}

List<Person> myPeople=new List<Person>();
myPeople.Add(new Person {"lisa","simpson",19});
myPeople.Add(new Person {"lilei","simpson",20});
// 使用索引器修改第一个值
myPeople[0]=new Person {"zhangsan","simpson",20} ;
...

public class PeopleCollection : IEnumerable
{
       private Dictionary<string,Person> listPeople= new Dictionary<string,Person>();
       // 基于一个字符串索引返回一个Person
       public Person this [string name]   
      {
             get{ return (Person)listPeople[name];}
             set{ listPeople[name]=value;} 
      }
 ...
}

//DataTableCollection类型，重载的索引器
public DataTable this[string name] {get;}
public DataTable this[string name,string tableNamespace]{get;}
public DataTable this[int index]{get;}

private int[,] myArray = new int[10,10];

public int this[int row ,int colum]
{/* 从二位数组中取值或赋值*/}

public interface IStringContainer
{
     //该接口定义了一个索引器，该索引器基于数字索引返回字符串
     string this[int index] {get;set;}
}