IEnumerable、GetEnumerator、IEnumerator之间的关系。

了解了这些也就明白了遍历的原理，晚安。

  1 using System;

  2 using System.Collections;

  3 

  4 public class Person

  5 {

  6     public Person(string fName, string lName)

  7     {

  8         this.firstName = fName;

  9         this.lastName = lName;

 10     }

 11 

 12     public string firstName;

 13     public string lastName;

 14 }

 15 

 16 public class People : IEnumerable

 17 {

 18     private Person[] _people;

 19     public People(Person[] pArray)

 20     {

 21         _people = new Person[pArray.Length];

 22 

 23         for (int i = 0; i < pArray.Length; i++)

 24         {

 25             _people[i] = pArray[i];

 26         }

 27     }

 28 

 29     IEnumerator IEnumerable.GetEnumerator()

 30     {

 31        return (IEnumerator) GetEnumerator();

 32     }

 33 

 34     public PeopleEnum GetEnumerator()

 35     {

 36         return new PeopleEnum(_people);

 37     }

 38 }

 39 

 40 public class PeopleEnum : IEnumerator

 41 {

 42     public Person[] _people;

 43 

 44     // Enumerators are positioned before the first element

 45     // until the first MoveNext() call.

 46     int position = -1;

 47 

 48     public PeopleEnum(Person[] list)

 49     {

 50         _people = list;

 51     }

 52 

 53     public bool MoveNext()

 54     {

 55         position++;

 56         return (position < _people.Length);

 57     }

 58 

 59     public void Reset()

 60     {

 61         position = -1;

 62     }

 63 

 64     object IEnumerator.Current

 65     {

 66         get

 67         {

 68             return Current;

 69         }

 70     }

 71 

 72     public Person Current

 73     {

 74         get

 75         {

 76             try

 77             {

 78                 return _people[position];

 79             }

 80             catch (IndexOutOfRangeException)

 81             {

 82                 throw new InvalidOperationException();

 83             }

 84         }

 85     }

 86 }

 87 

 88 class App

 89 {

 90     static void Main()

 91     {

 92         Person[] peopleArray = new Person[3]

 93         {

 94             new Person("John", "Smith"),

 95             new Person("Jim", "Johnson"),

 96             new Person("Sue", "Rabon"),

 97         };

 98 

 99         People peopleList = new People(peopleArray);

100         foreach (Person p in peopleList)

101             Console.WriteLine(p.firstName + " " + p.lastName);

102 

103     }

104 }

105 

106 /* This code produces output similar to the following:

107  *

108  * John Smith

109  * Jim Johnson

110  * Sue Rabon

111  *

112  */