什么是索引指示器

什么是索引指示器

實現(xiàn)索引指示器（indexer）的類可以象數(shù)組那樣使用其實例后的對象，但與數(shù)組不同的是索引指示器的參數(shù)類型不僅限于int

簡潔來說，其本質(zhì)就是一個含參數(shù)屬性

示例：

usingSystem;

usingSystem.Collections.Generic;

usingSystem.Text;

namespaceExample08

{

publicclassPoint

{

privatedoublex,y;

publicPoint(doubleX,doubleY)

{

x=X;

y=Y;

}

//重寫ToString方法便利輸出

publicoverridestringToString()

{

returnString.Format(“X:{0},Y:{1}”,x,y);

}

}

publicclassPoints

{

Pointpoints;

publicPoints(PointPoints)

{

points=Points;

}

publicintPointNumber

{

get

{

returnpoints.Length;

}

}

//實現(xiàn)索引訪問器

publicPointthis

{

get

{

returnpoints;

}

}

}

//索引指示器的實質(zhì)是含參屬性，參數(shù)并不只限于int

classWeatherOfWeek

{

publicstringthis

{

get

{

//留意case段使用return直接返回所以不需要break

switch(Index)

{

case0:

{

return“Todayiscloudy!”;

}

case5:

{

return“Todayisthundershower!”;

}

default:

{

return“Todayisfine!”;

}

}

}

}

publicstringthis

{

get

{

stringTodayWeather=null;

//switch的標準寫法

switch(Day)

{

case“Sunday”:

{

TodayWeather=“Todayiscloudy!”;

break;

}

case“Friday”:

{

TodayWeather=“Todayisthundershower!”;

break;

}

default:

{

TodayWeather=“Todayisfine!”;

break;

}

}

returnTodayWeather;

}

}

}

classProgram

{

staticvoidMain(stringargs)

{

PointtmpPoints=newPoint;

for(inti=0;i<tmpPoints.Length;i++)

{

tmpPoints=newPoint(i,Math.Sin(i));

}

PointstmpObj=newPoints(tmpPoints);

for(inti=0;i<tmpObj.PointNumber;i++)

{

Console.WriteLine(tmpObj);

}

stringWeek=newstring{“Sunday”,“Monday”,“Tuesday”,“Wednesday”,“Thursday”,“Friday”,“Staurday”};

WeatherOfWeektmpWeatherOfWeek=newWeatherOfWeek();

for(inti=0;i<6;i++)

{

Console.WriteLine(tmpWeatherOfWeek);

}

foreach(stringtmpDayinWeek)

{

Console.WriteLine(tmpWeatherOfWeek);

}

Console.ReadLine();

}

}

}

結(jié)果：

X:0,Y:0

X:1,Y:0.841470984807897

X:2,Y:0.909297426825682

X:3,Y:0.141120008059867

X:4,Y:-0.756802495307928

X:5,Y:-0.958924274663138

X:6,Y:-0.279415498198926

X:7,Y:0.656986598718789

X:8,Y:0.989358246623382

X:9,Y:0.412118485241757

Todayiscloudy!

Todayisfine!

Todayisfine!

Todayisfine!

Todayisfine!

Todayisthundershower!

Toda