C#中IEnumerable接口介绍并实现自定义集合

    public static void Test3()
    {
        MyInt temp = new MyInt();
        foreach (int item in temp)
        Console.WriteLine(item);
    }
    //foreach的必须要实现IEnumerable和IEnumerator的接口
    public class MyInt : IEnumerable
    {
        int[] temp = { 1, 32, 43, 343 };

        public IEnumerator GetEnumerator()
        {
            return temp.GetEnumerator();
        }
    }

    public static void Test1()
    {
        int[] myArray = { 1, 32, 43, 343 };
        //获取要遍历的枚举数
        IEnumerator myie = myArray.GetEnumerator();
        //重置当前项，相当于把指针移到初始位置：position = -1; 一开始认识数组的索引从“0”开始
        myie.Reset();
        //向前移动一个索引，返回Bool类型，判断是否超出下标
        while (myie.MoveNext())
        {
            int i = (int)myie.Current;//从Object转成对应类型
            Console.WriteLine("Value: {0}", i);
        }
    }

//lamda表达式在数组中查询
        public static void Test2()
        {
            List<string> fruits =
              new List<string> { "apple", "passionfruit", "banana", "mango",
                    "orange", "blueberry", "grape", "strawberry" };
            //List<string> query = fruits.Where(fruit => fruit.Length < 6).ToList();
            IEnumerable<string> query = fruits.Where(fruit => fruit.Length < 6);
            foreach (string fruit in query)
                Console.WriteLine(fruit);
        }

namespace ConsoleApplication1
{
    //定义Person类
    public class Person
    {
        //初始化
        public Person(string fName, string lName)
        {
            this.firstName = fName;
            this.lastName = lName;
        }

        //类成员
        public string firstName;
        public string lastName;
    }

    //实现接口
    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();
        }

        //获取枚举数
        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;
        }

        //向下推移索引，返回Bool类型值
        public bool MoveNext()
        {
            position++;
            return (position < _people.Length);
        }

        //重置默认索引位置，默认下标为0
        public void Reset()
        {
            position = -1;
        }

        object IEnumerator.Current
        {
            get
            {
                return Current;
            }
        }

        //当前索引值
        public Person Current
        {
            get
            {
                try
                {
                    return _people[position];
                }
                catch (IndexOutOfRangeException)
                {
                    throw new InvalidOperationException();
                }
            }
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            //实例化Person
            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);
        }
    }
}