C#is运算符的作用

is运算符的含义:检查对象是不是给定类型,或者是否可以转换为给定类型,如果是,这个运算符就返回True.

is运算符的语法:<operand> is <type>

这个表达式的结果如下:如果<type>是一个类类型,而<operand>也是该类型,或者它继承了该类型,或者它可以封箱到该类型中,则结果返回True.

如果<type>是一个接口类型,而<operand>也是该类型,或者它是实现该接口的类型,则结果返回True.

　　　　　　　　　　 如果<type>是一个值类型,而<operand>也是该类型,或者它可以拆箱到该类型中,则返回True.

is实例:

 namespace Chapter11
 {
     class Checker
     {
         public void Check(object param1)
         {
             if (param1 is ClassA)
                 Console.WriteLine("Variable can be converted to ClassA");
             else
                 Console.WriteLine("Variable can't be converted to ClassA.");

             if (param1 is IMyInterface)
                 Console.WriteLine("Variable can be converted to IMyInterface.");
             else
                 Console.WriteLine("Variable can't converted to IMyInterface.");

             if (param1 is MyStruct)
                 Console.WriteLine("Variable can be converted to MyStruct.");
             else
                 Console.WriteLine("Variable can't be converted to MyStruct.");
         }
     }
     interface IMyInterface
     { }
     class ClassA : IMyInterface
     { }
     class ClassB :IMyInterface
     { }

     class ClassC
     { }

     class classD : ClassA
     { }

     struct MyStruct : IMyInterface
     { }
     class Program
     {
         static void Main(string[] args)
         {
             Checker check = new Checker();
             ClassA try1 = new ClassA();
             ClassB try2 = new ClassB();
             ClassC try3 = new ClassC();
             classD try4 = new classD();
             MyStruct try5 = new MyStruct();
             object try6 = try5;
             Console.WriteLine("Analyzing ClassA type variable:");
             check.Check(try1);
             Console.WriteLine("Analyzing ClassB type variable:");
             check.Check(try2);
             Console.WriteLine("Analyzing ClassC type variable:");
             check.Check(try3);
             Console.WriteLine("Analyzing ClassD type variable:");
             check.Check(try4);
             Console.WriteLine("Analyzing MyStruct type variable:");
             check.Check(try5);
             Console.WriteLine("Analyzing boxed MyStruct type variable:");
             check.Check(try6);
             Console.ReadKey();
         }
     }
 }