C# yield return 的作用

using System;
using System.Collections;
using System.Threading;

namespace YieldKeywordTestingProject
{
/// <summary>
/// jave.lin
/// 20114-02-12
/// </summary>
class Program
{
static bool delay = true;

static void Main(string[] args)
{
var result = getResult();
Console.WriteLine("first writeline : " + result.Current);
while (result.MoveNext())
{
Console.WriteLine("outside writeLine : {0}", result.Current);
}
Console.WriteLine("yield return Over!!!");
Console.ReadLine();
}

static IEnumerator getResult()
{
//var arr = Array.CreateInstance(typeof(Program), 1);
var arr = new int[] { 1, 2, 3, 45, 23, 23, 4, 3213 };
foreach (var item in arr)
{
yield return item;
Console.WriteLine(item);
// 关键看这里，如果delay为true时的输出，是与delay为false一样的；
// 这样你就对yield return 的理解更深了；
if (delay) Thread.Sleep(100);
}
}
}
}