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C#基础——索引器

2010-01-05 23:33 309 查看

索引器在语法上方便创建客户端应用程序可将其作为数组访问的类、结构或接口。

索引器是在主要用于封装内部集合或数组的类型中实现的，使用this关键字。

class TempRecord
{
private float[] temps=new float[10]{56.2F, 56.7F, 56.5F, 56.9F, 58.8F,
61.3F, 65.9F, 62.1F, 59.2F, 57.5F};
public int Length
{
get{return temps.Length;}
}

public float this[int index]
{
get{return temps[index];}
set {temps[index]=value;}
}
}
public class MyClass
{
public static void Main()
{
TempRecord tempRecord=new TempRecord();
tempRecord[3]=58.3F;
tempRecord[5]=60.1F;

for(int i=0;i<tempRecord.Length;i++)
{
Console.WriteLine("Element #{0} = {1}", (i+1), tempRecord[i]);
}

Console.ReadLine();
}
}

.src_container{background-color:#e7e5dc; width:99%; overflow:hidden; margin:12px 0 12px 0 !important; padding:0px 3px 3px 0px}
.src_container .titlebar{ background-color:#d4dfff; border:1px solid #4f81bd; border-bottom:0; padding:3px 24px; margin:0; width:auto; line-height:120%; overflow:hidden; text-align:left; font-size:12px}
.src_container .toolbar{ display:inline; font-weight:normal; font-size:100%; float:right; cursor:hand; color:#00f; text-align:left; overflow:hidden}
.toolbar span.button{ display:inline; font-weight:normal; font-size:100%; cursor:hand; color:#00f; text-align:left; overflow:hidden; cursor:pointer;}
.src_container div.clientarea{ background-color:white; border:1px solid #4f81bd; margin:0; width:auto !important; width:100%; height:auto; overflow:auto; text-align:left; font-size:12px; font-family: "Courier New","Consolas","Fixedsys",courier,monospace,serif}
.src_container ol.mainarea{ padding:0 0 0 52px; margin:0; background-color:#f7f7ff !important}
.number_show{ padding-left:52px !important; list-style:decimal outside !important}
.number_show li{ list-style:decimal outside !important; border-left:1px dotted #4f81bd}
.number_hide{ padding-left:0px !important; list-style-type:none !important}
.number_hide li{ list-style-type:none !important; border-left:0px}
ol.mainarea li{ display:list-item !important; font-size:12px !important; margin:0 !important; line-height:18px !important; padding:0 0 0 0px !important; background-color:#f7f7ff !important; color:#4f81bd}
ol.mainarea li pre{color:black; line-height:18px; padding:0 0 0 12px !important; margin:0em; background-color:#fff !important}
.linewrap ol.mainarea li pre{white-space:pre-wrap; white-space:-moz-pre-wrapwhite-space:-pre-wrap; white-space:-o-pre-wrap; word-wrap:break-word}
ol.mainarea li pre.alt{ background-color:#f7f7ff !important}
function CopyCode(key){var codeElement=null;var trElements=document.all.tags("ol");var i;for(i=0;i 输出：

C#并不将索引类型限制为整数：

class DayCollection
{
string [] days={ "Sun", "Mon", "Tues", "Wed", "Thurs", "Fri", "Sat" };
private int GetDay(string testDay)
{
int i = 0;
foreach (string day in days)
{
if (day == testDay)
{
return i;
}
i++;
}
return -1;

}
public int this[string day]
{
get{return (GetDay(day));}
}
}
public class Program
{
public static void Main()
{
DayCollection week=new DayCollection();
Console.WriteLine(week["Fri"]);
Console.WriteLine(week["Made-up Day"]);
Console.ReadLine();
}
}

在接口使用索引器：

public interface IIndexInterface
{
int this[int index]
{
get;
set;
}
}
class IndexClass:IIndexInterface
{
public int [] arr=new int[100];
public int this[int index]
{
get
{
if (index < 0 || index >= 100)
{
return 0;
}
else
{
return arr[index];
}
}
set
{
if (!(index < 0 || index >= 100))
{
arr[index] = value;
}
}

}
}
public class Program
{
public static void Main()
{
IndexClass test=new IndexClass();
test[2]=4;
test[5]=32;
for(int i=0;i<10;i++)
{
Console.WriteLine("Element #{0} = {1}", i, test[i]);
}
Console.ReadLine();
}
}

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