C#is運算子的作用

標籤：

is運算子的含義:檢查對象是不是給定類型,或者是否可以轉換為給定類型,如果是,這個運算子就返回True.

is運算子的文法:<operand> is <type>

這個運算式的結果如下:如果<type>是一個類類型,而<operand>也是該類型,或者它繼承了該類型,或者它可以封箱到該類型中,則結果返回True.

                             如果<type>是一個介面類型,而<operand>也是該類型,或者它是實現該介面的類型,則結果返回True.

　　　　　　　　　　 如果<type>是一個實值型別,而<operand>也是該類型,或者它可以拆箱到該類型中,則返回True.

is執行個體:

 1 namespace Chapter11 2 { 3     class Checker 4     { 5         public void Check(object param1) 6         { 7             if (param1 is ClassA) 8                 Console.WriteLine("Variable can be converted to ClassA"); 9             else10                 Console.WriteLine("Variable can‘t be converted to ClassA.");11 12             if (param1 is IMyInterface)13                 Console.WriteLine("Variable can be converted to IMyInterface.");14             else15                 Console.WriteLine("Variable can‘t converted to IMyInterface.");16 17             if (param1 is MyStruct)18                 Console.WriteLine("Variable can be converted to MyStruct.");19             else20                 Console.WriteLine("Variable can‘t be converted to MyStruct.");21         }22     }23     interface IMyInterface24     { }25     class ClassA : IMyInterface26     { }27     class ClassB :IMyInterface28     { }29 30     class ClassC31     { }32 33     class classD : ClassA34     { }35 36     struct MyStruct : IMyInterface37     { }38     class Program39     {40         static void Main(string[] args)41         {42             Checker check = new Checker();43             ClassA try1 = new ClassA();44             ClassB try2 = new ClassB();45             ClassC try3 = new ClassC();46             classD try4 = new classD();47             MyStruct try5 = new MyStruct();48             object try6 = try5;49             Console.WriteLine("Analyzing ClassA type variable:");50             check.Check(try1);51             Console.WriteLine("Analyzing ClassB type variable:");52             check.Check(try2);53             Console.WriteLine("Analyzing ClassC type variable:");54             check.Check(try3);55             Console.WriteLine("Analyzing ClassD type variable:");56             check.Check(try4);57             Console.WriteLine("Analyzing MyStruct type variable:");58             check.Check(try5);59             Console.WriteLine("Analyzing boxed MyStruct type variable:");60             check.Check(try6);61             Console.ReadKey();62         }63     }64 }

 

C#is運算子的作用