public

 

class

 YieldReturn

    {

        

//

yield return用于无缝实现迭代模式。

   

        

string

[] strArr;

        

public

 YieldReturn(

params

 

string

[] arr)

        {

            strArr 

=

 

new

 

string

[arr.Length];

            arr.CopyTo(strArr, 

0

);

            

        }

        

       

        

//

-------一个枚举对象可以对应多个枚举

        

///

 

<summary>

        

///

 反序输出

        

///

 

</summary>

        

public

 IEnumerable

<

string

>

 Reverse

        {

            

get

            {

                

for

 (

int

 i 

=

 strArr.Length 

-

 

1

; i 

>=

 

0

; i

--

)

                    

yield

 

return

 strArr[i];

            }

        }

        

///

 

<summary>

        

///

 顺序输出

        

///

 

</summary>

        

public

 IEnumerable

<

string

>

 PosEven

        {

            

get

            {

                

for

 (

int

 i

=

0

;i

<

strArr.Length; i

++

)

                    

yield

 

return

 strArr[i];

            }

        }

        

public

 IEnumerable

<

string

>

 Concat

        {

            

get

            {

                

foreach

 (

string

 s 

in

 Reverse)

                    

yield

 

return

 s;

                

foreach

 (

string

 s 

in

 PosEven)

                    

yield

 

return

 s;

            }

        }

        

    }

 实现：

      

public

 

static

 

void

 yieldreturn()

        {

            YieldReturn yr 

=

 

new

 YieldReturn(

"

aaa

"

, 

"

bbb

"

, 

"

ccc

"

);

            Console.WriteLine(

"

-----Reverse:

"

);

            

foreach

 (

string

 s 

in

 yr.Reverse)

                Console .WriteLine (s);

            Console.WriteLine(

"

-----PosEven:

"

);

            

foreach

 (

string

 s 

in

 yr.PosEven)

                Console.WriteLine(s);

            Console.WriteLine(

"

-----Concat:

"

);

            

foreach

 (

string

 s 

in

 yr.Concat)

                Console.WriteLine(s);

        }