c# IEnumerable和IEnumerator枚举器

一： IEnumerable　　

　　公开枚举数，该枚举数支持在非泛型集合上进行简单迭代。

　　IEnumerable是可以枚举的所有非泛型集合的基接口,IEnumerable包含单个方法GetEnumerator，它将返回IEnumerator。 IEnumerator提供了通过公开循环访问集合的能力Current属性和MoveNext和Reset方法。【官方解释】

 1 public class Computer : IEnumerator
 2     {
 3         List<T> list = null;
 4         public Computer()
 5         {
 6             list = new List<T>();
 7         }
 8 
 9         public void Add(string str)
10         {
11             list.Add(str);
12         }
13 
14         public IEnumerator GetEnumerator()
15         {
16             for (int i = 0; i < list.Count; i++)
17             {
18                 yield return list[i];
19             }
20         }
21     }

View Code

　　官方示例：实现IEnumerable和IEnumerator为自定义集合的接口（foreach的内部实现）

 1 public class Person
 2     {
 3         public Person(string fName, string lName)
 4         {
 5             this.firstName = fName;
 6             this.lastName = lName;
 7         }
 8 
 9         public string firstName;
10         public string lastName;
11     }
12 
13     public class People : IEnumerable
14     {
15         private Person[] _people;
16         public People(Person[] pArray)
17         {
18             _people = new Person[pArray.Length];
19 
20             for (int i = 0; i < pArray.Length; i++)
21             {
22                 _people[i] = pArray[i];
23             }
24         }
25 
26         IEnumerator IEnumerable.GetEnumerator()
27         {
28             return (IEnumerator)GetEnumerator();
29         }
30 
31         public PeopleEnum GetEnumerator()
32         {
33             return new PeopleEnum(_people);
34         }
35     }
36 
37     public class PeopleEnum : IEnumerator
38     {
39         public Person[] _people;
40 
41         int position = -1;
42 
43         public PeopleEnum(Person[] list)
44         {
45             _people = list;
46         }
47 
48         public bool MoveNext()
49         {
50             position++;
51             return (position < _people.Length);
52         }
53 
54         public void Reset()
55         {
56             position = -1;
57         }
58 
59         object IEnumerator.Current
60         {
61             get
62             {
63                 return Current;
64             }
65         }
66 
67         public Person Current
68         {
69             get
70             {
71                 try
72                 {
73                     return _people[position];
74                 }
75                 catch (IndexOutOfRangeException)
76                 {
77                     throw new InvalidOperationException();
78                 }
79             }
80         }
81     }
82 class Program
83     {
84         static void Main(string[] args)
85         {
86             Person[] peopleArray = new Person[3]
87             {
88                 new Person("John", "Smith"),
89                 new Person("Jim", "Johnson"),
90                 new Person("Sue", "Rabon"),
91             };
92 
93             People peopleList = new People(peopleArray);
94 
95             foreach (Person p in peopleList)
96                 Console.WriteLine(p.firstName + " " + p.lastName);
97         }
98     }

View Code

二：IEnumerator

　　支持对非泛型集合的简单迭代。

　　C# 语言的 foreach 语句隐藏了枚举数的复杂性。因此，建议使用foreach而不是直接操作枚举数。

c# IEnumerable和IEnumerator枚举器

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