C# Common Keyword II

【C# Common Keyword II】

1、as 运算符用于在兼容的引用类型之间执行某些类型的转换。

   class csrefKeywordsOperators
   {
       class Base
       {
           public override string  ToString()
           {
                 return "Base";
           }
       }
       class Derived : Base 
       { }

       class Program
       {
           static void Main()
           {

               Derived d = new Derived();

               Base b = d as Base;
               if (b != null)
               {
                   Console.WriteLine(b.ToString());
               }

           }
       }
   }

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