C#的装箱和拆箱

using System;
using System.Collections;
using System.Collections.Generic;
/*
 * 装箱和拆箱操作很容易使用，但性能损失比较大，遍历许多项时尤其如此。
 * 
 */
namespace Csharp
{    
    class Program
    {

        static void Main(string[] args)
        {
            var list = new ArrayList();
            list.Add(44);   //boxing--convert a value type to a reference type
            int i1 = (int)list[0];  //unboxing--convert a reference type to a value type

            var list1 = new List<int>();
            list1.Add(55);  //no boxing -- value types are stored in the List<int>
            int i2 = list1[0];  //no unboxing, no cast needed
            foreach (int item in list)
            {
                Console.WriteLine(item);  //unboxing
            }
            foreach (int item in list1)
            {
                Console.WriteLine(item); 
            }

            Console.ReadKey();
        }
       
    }

   
}