using System;

using System.Collections;

public class Program

{

    public 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);

    }

}

​

public class Person

{

    public Person(string fName, string lName)

    {

        this.firstName = fName;

        this.lastName = lName;

    }

​

    public string firstName;

    public string lastName;

}

​

// Collection of Person objects. This class

// implements IEnumerable so that it can be used

// with ForEach syntax.

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];

        }

    }

​

    // Implementation for the GetEnumerator method.

    IEnumerator IEnumerable.GetEnumerator()

    {

       return new PeopleEnum(_people);

    }    

}

​

// When you implement IEnumerable, you must also implement IEnumerator.

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();

            }

        }

    }

}