c#-foreach的秘密

foreach的秘密

class Program

{

static void Main(string[] args)

{

//创建Person的对象

Person p1=new Person();

//遍历p1因为实现了IEnumerable接口

foreach (var item in p1)

{

Console.WriteLine(item);

}

Console.ReadKey();

}

}

//实现了Ienumerable接口就可以遍历对象了

//实现IIndextor因为EnumeratorIndex是泛型类需要实现IIndextor接口

public class Person:IEnumerable,IIndextor

{

public string[] strs = new string[6];

public string this[int Index]

{

get { return strs[Index]; }

set { strs[Index] = value; }

}

public Person()

{

strs[0] = "3sfgew";

strs[1] = "322";

strs[2] = "34";

strs[3] = "3434";

strs[4] = "3ww";

strs[5] = "3sdfe";

}

public IEnumerator GetEnumerator()

{

//返回Ienumerator的实现类

return new EnumeratorIndex<Person>(this);

}

public int IndexLength

{

get { return strs.Length; }

}

}

//定义索引器的接口

public interface IIndextor

{

string this[int Index] { get; }

int IndexLength { get; }

}

public class EnumeratorIndex<T> : IEnumerator where T:IIndextor

{

T p1;

int Index;

//构造函数

public EnumeratorIndex(T p1)

{

//给必须的对象赋值

//Index的初始值必须是-1

Index = -1;

this.p1 = p1;

}

//返回当前的对象

public object Current

{

get { return p1[Index]; }

}

//使索引前进到下一个

public bool MoveNext()

{

if (Index < p1.IndexLength - 1)

{

Index++;

return true;

}

else

{

return false;

}

}

//初始化索引

public void Reset()

{

Index = -1;

}

}