调试易

get 
{
   return myArray[index];
}
set 
{
   myArray[index] = value;
}

要继承一些接口，如下是个例子：using System;
using System.Collections;
namespace Fetri.oilManageClass
{
    public class SysnoteEntityCollection:IList,ICollection,IEnumerable
    {
        System.Collections.ArrayList elements;
        public SysnoteEntityCollection()
        {
            elements=new System.Collections.ArrayList();
        }        public SysnoteEntity this[int index]
        {
            get
            {
                return (SysnoteEntity)this.elements[index];
            }
            set
            {
                this.elements[index]=value;
            }
        }        int IList.IndexOf(object value)
        {
            return ((SysnoteEntityCollection)this).IndexOf((SysnoteEntity)value);
        }        public int IndexOf(SysnoteEntity value)
        {
            return this.elements.IndexOf(value);
        }        public bool IsReadOnly
        {
            get
            {
                return this.elements.IsReadOnly;
            }
        }        object IList.this[int index]
        {
            get
            {
                return ((SysnoteEntityCollection)this)[index];
            }
            set
            {
                ((SysnoteEntityCollection)this)[index]=(SysnoteEntity)value;
            }
        }        public bool IsFixedSize
        {
            get
            {
                return this.elements.IsSynchronized;
            }
        }        public bool IsSynchronized
        {
            get
            {
                return true;
            }
        }        public int Count
        {
            get
            {
                return this.elements.Count;
            }
        }        public void CopyTo(System.Array array,int index)
        {
            this.elements.CopyTo(array,index);
        }        public object SyncRoot
        {
            get
            {
                return this.elements.SyncRoot;
            }
        }        public System.Collections.IEnumerator GetEnumerator()
        {
            return this.elements.GetEnumerator();
        }        public int Add(SysnoteEntity value)
        {
            return this.elements.Add(value);
        }        int IList.Add(object value)
        {
            return ((SysnoteEntityCollection)this).Add((SysnoteEntity)value);
        }        void IList.Insert(int index, object value)
        {
            ((SysnoteEntityCollection)this).Insert(index,(SysnoteEntity)value);
        }        public void Insert(int index, SysnoteEntity value)
        {
            this.elements.Insert(index,value);
        }        public void RemoveAt(int index)
        {
            this.elements.RemoveAt(index);
        }        void IList.Remove(object value)
        {
            ((SysnoteEntityCollection)this).Remove((SysnoteEntity)value);
        }        public void Remove(SysnoteEntity value)
        {
            this.elements.Remove(value);
        }        bool IList.Contains(object value)
        {
            return ((SysnoteEntityCollection)this).Contains((SysnoteEntity)value);
        }        public bool Contains(SysnoteEntity value)
        {
            return this.elements.Contains(value);
        }        public void Clear()
        {
            this.elements.Clear();
        }
    }
}

this [int index] 
索引

用索引器就可以了不用那么麻烦去实现那些接口把！！
例如：1： 定义类
class MyArray
{
ArrayList list = new ArrayList();
.....  public object this[int index]
  {
      get{return this.list[index];}
      set{this.list[index] = value;}
  }
.....
}2: 运用MyArray _arrayObj = new MyArray()；
object obj = _arrayObj［２］;

index不行，因为如果这样a[i]就作不了引用参数了
要重载[]