C# 2.0学习之--集合2

编译与执行：
csc tokens2.cs
tokens2

tokens2.cs :

//Copyright (C) Microsoft Corporation. All rights reserved.

// tokens2.cs
using System;
using System.Collections;

public class Tokens: IEnumerable
{
private string[] elements;

Tokens(string source, char[] delimiters)
{
elements = source.Split(delimiters);
}

// IEnumerable Interface Implementation:

public TokenEnumerator GetEnumerator() // non-IEnumerable version
{
return new TokenEnumerator(this);
}

IEnumerator IEnumerable.GetEnumerator() // IEnumerable version
{
return (IEnumerator) new TokenEnumerator(this);
}

// Inner class implements IEnumerator interface:

public class TokenEnumerator: IEnumerator
{
private int position = -1;
private Tokens t;

public TokenEnumerator(Tokens t)
{
this.t = t;
}

public bool MoveNext()
{
if (position < t.elements.Length - 1)
{
position++;
return true;
}
else
{
return false;
}
}

public void Reset()
{
position = -1;
}

public string Current // non-IEnumerator version: type-safe
{
get
{
return t.elements[position];
}
}

object IEnumerator.Current // IEnumerator version: returns object
{
get
{
return t.elements[position];
}
}
}

// Test Tokens, TokenEnumerator

static void Main()
{
Tokens f = new Tokens("This is a well-done program.",
new char [] {' ','-'});
foreach (string item in f) // try changing string to int
{
Console.WriteLine(item);
}
}
}