C#中IEnumerable接口用法实例分析

using System;
using System.Collections;
public class Person
{
 public Person(string fName, string lName)
 {
  this.firstName = fName;
  this.lastName = lName;
 }
 public string firstName;
 public string lastName;
}
public class People : IEnumerable
{
 private Person[] _people;
 public People(Person[] pArray)
 {
  _people = new Person[pArray.Length];
  for (int i = 0; i < pArray.Length; i++)
  {
   _people[i] = pArray[i];
  }
 }
 IEnumerator IEnumerable.GetEnumerator()
 {
  return (IEnumerator) GetEnumerator();
 }
 public PeopleEnum GetEnumerator()
 {
  return new PeopleEnum(_people);
 }
}
public class PeopleEnum : IEnumerator
{
 public Person[] _people;
 // Enumerators are positioned before the first element
 // until the first MoveNext() call.
 int position = -1;
 public PeopleEnum(Person[] list)
 {
  _people = list;
 }
 public bool MoveNext()
 {
  position++;
  return (position < _people.Length);
 }
 public void Reset()
 {
  position = -1;
 }
 object IEnumerator.Current
 {
  get
  {
   return Current;
  }
 }
 public Person Current
 {
  get
  {
   try
   {
    return _people[position];
   }
   catch (IndexOutOfRangeException)
   {
    throw new InvalidOperationException();
   }
  }
 }
}
class App
{
 static void Main()
 {
  Person[] peopleArray = new Person[3]
  {
   new Person("John", "Smith"),
   new Person("Jim", "Johnson"),
   new Person("Sue", "Rabon"),
  };
  People peopleList = new People(peopleArray);
  foreach (Person p in peopleList)
   Console.WriteLine(p.firstName + " " + p.lastName);
 }
}
/* This code produces output similar to the following:
 *
 * John Smith
 * Jim Johnson
 * Sue Rabon
 *
 */