分不清IEnumerable和IEnumerator

首先看几个单词

Enum 枚举类型

IEnumerator 枚举器

IEnumerable 可枚举

从单词上大概可以看出IEnumerator是实际枚举器

查看源码

源码分析：

1 IEnumerable接口仅定义了一个返回IEnumerator类型的GetEnumerator方法

2 IEumerator接口定义了三个方法，Current获取当前的对象返回Object类型，MoveNext指针下移，Reset将指针重置

3 IEnumerator才是真正的集合遍历器，为了实现集合对象的遍历，必须实现IEnumerable接口

操作实例

1 定义实体类球类

 1 namespace IEnumerableTest
 2 {
 3     class Ball
 4     {
 5         //编号
 6         public int No { get; set; }
 7         //颜色
 8         public string Color { get; set; }
 9         //球值
10         public string Data { get; set; }
11     }
12 }

View Code

2 定义BallEnum 继承IEnumerator，实现MoveNext,Reset,Current方法

 1 class BallEnum:IEnumerator
 2     {
 3         public Ball[] _ball;
 4         int position = -1;
 5         public BallEnum(Ball[] ball)
 6         {
 7              _ball=ball;
 8         }
 9         public bool MoveNext()
10         {
11             position++;
12             return (position < _ball.Length);
13         }
14         public void Reset()
15         {
16             position = -1;
17         }
18         public object Current
19         {
20             get {
21                 try
22                 {
23                     return _ball[position];
24                 }
25                 catch (IndexOutOfRangeException)
26                 {
27                     throw new InvalidOperationException();
28                 }
29             }
30         }
31         public void Dispose()
32         {
33             throw new NotImplementedException();
34         }
35     }

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3 定义实体类摇奖机继承接口IEnumerable 实现GetEnumerator方法

 1 class LotteryMachine:IEnumerable
 2     {
 3         private Ball[] _balls;
 4         public LotteryMachine(Ball[]balls)
 5         {
 6             _balls = new Ball[balls.Length];
 7             for (int i = 0; i < balls.Length; i++)
 8             {
 9                 _balls[i] = balls[i];
10             }
11         }
12         IEnumerator IEnumerable.GetEnumerator()
13         {
14             return (IEnumerator)new BallEnum(_balls);
15         }
16     }

View Code

4 调用

 1             //当前号码
 2             int No;
 3             //抽取次数
 4             int times = 5;
 5             StringBuilder sb = new StringBuilder();
 6             //添加球
 7             Ball[] balls = new Ball[10]{
 8                 new Ball() { No = 1, Color = "bule" ,Data="34"},
 9                 new Ball() { No = 2, Color = "red" ,Data="21"},
10                 new Ball() { No = 3, Color = "black",Data="01" },
11                 new Ball() { No = 4, Color = "green",Data="03" },
12                 new Ball() { No = 5, Color = "yellow",Data="12" },
13                 new Ball() { No = 6, Color = "pink",Data="18" },
14                 new Ball() { No = 7, Color = "orange",Data="58" },
15                 new Ball() { No = 8, Color = "gray",Data="90" },
16                 new Ball() { No = 9, Color = "white",Data="45" },
17                 new Ball() { No = 10, Color = "purples",Data="00" },
18             };
19             //摇奖机，并把球放进去
20             LotteryMachine lotteryMachine = new LotteryMachine(balls);
21             //动起来
22             Random r = new Random();
23             for (int i = 0; i < times; i++)
24             {
25                 No = r.Next(1, balls.Length + 1);
26                 foreach (Ball ball in lotteryMachine)
27                 {
28                     if (ball.No==No)
29                     {
30                         sb.Append(ball.Data);
31                     }
32                 }
33                 if (i<times)
34                 {
35                     sb.Append(" ");
36                 }
37             }
38             Console.WriteLine("本期中奖号码：");
39             Console.WriteLine(sb.ToString());
40             Console.ReadKey();
41

View Code

5 结果