1. 示例：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Collections;
namespace NetTest
{
public class TestIteration
{
public void Test()
{
SevenColor colorIteration = new SevenColor();
foreach (string p in colorIteration)
{
Console.Out.WriteLine(p);
}
Console.Out.WriteLine("-------------Desc-------------------");
foreach (string c in colorIteration.DescColorIteration(1, 5))
{
Console.Out.WriteLine(c);
}
Console.Out.WriteLine("--------------multi yield---------");
foreach (string c in colorIteration.GetMutipleYied())
{
Console.Out.WriteLine(c);
}
}
}
public class SevenColor : IEnumerable
{
string[] mColor={"red","orange","yellow","green","cyan","blue","purple"};
#region IEnumerable Members
/*
迭代器代码使用 yield return 语句依次返回每个元素。yield break 将终止迭代。
可以在类中实现多个迭代器。每个迭代器都必须像任何类成员一样有唯一的名称，
并且可以在 foreach 语句中被客户端代码调用，如下所示：foreach(int x in SampleClass.Iterator2){}
*/
public IEnumerator GetEnumerator()
{
for (int i = 0; i < mColor.Length; i++)
{
yield return mColor[i];
}
}
#endregion
//注意，这里返回的是IEnumerable
public System.Collections.IEnumerable DescColorIteration(int start, int end)
{
for (int i = 0; i <=end; i++)
{
yield return mColor[end-i];
}
}
//在 foreach 循环的每次后续迭代（或对 IEnumerator.MoveNext 的直接调用）中，
//下一个迭代器代码体将从前一个 yield 语句之后开始，并继续下一个语句直至到达迭代器体的结尾或遇到 yield break 语句
public IEnumerable GetMutipleYied()
{
yield return "hello";
yield return "I am";
yield return "Jack";
yield return "wang";
}
}
}
2. 输出
