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IEnumerable and IEnumerator

IEnumerator defines the protocol for traversable or enumerable collections.

Its declaration is as follows:


public interface IEnumerator
{
    bool MoveNext();
    object Current { get; }
    void Reset();
}

IEnumerable is IEnumerator provider:


public interface IEnumerable
{
    IEnumerator GetEnumerator();
}

The following example illustrates how to use IEnumerable and IEnumerator:


using System;
using System.Collections;

class Sample
{
    public static void Main()
    {
        string s = "java2s.com";


        IEnumerator rator = s.GetEnumerator();
        while (rator.MoveNext())
        {
            char c = (char)rator.Current;
            Console.Write(c + ".");
        }
    }
}

The output:


j.a.v.a.2.s...c.o.m.

C# provides a shortcut: foreach statement.


using System;
using System.Collections;

class Sample
{
    public static void Main()
    {
        string s = "Hello";  // The String class implements IEnumerable

        foreach (char c in s) Console.Write(c + ".");

    }
}

The output:


H.e.l.l.o.

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