关于c#中方法覆盖的问题

Question

class xxx
{
   public virtual void function1()
   {
     // Some code here
   }
}

class  yyy : xxx
{
   public override void function1()
   {
    // some code here
   }
}

class result
{
   public result(){}

   // In the main i write as

   xxx xobj = new yyy();
   xobj.function1(); // by calling this function1 in yyy will invoked

   yyy yobj = new xxx();
   yobj.function1()     // which function will be called here
}

PLE

Answer 1

好吧,首先:

yyy yobj = new xxx();
yobj.function1();

将导致编译错误. yyy是一个xxx,但xxx不是一个yyy.

其次:

xxx xobj = new yyy();
xobj.function1();

将导致function1()类xxx被执行,因为变量是类型xxx.要在类上调用该方法,yyy您需要将变量强制转换为类型yyy

xxx xobj = new yyy();
((yyy)xobj).function1();