如何在函数中判断传递的对象指向的是哪个类

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本文介绍了一个C++程序，该程序通过使用dynamic_cast操作符来判断一个基类指针所指向的对象的具体类型，并返回相应的字符串表示。这适用于理解C++中的多态性和动态类型检查。

Three classes A, B and C are shown below:

class A {
public:
virtual ~A() {};
};
class B: public A {};
class C: public B {};

You are to implement a function string verify(A *), such that it returns "grandpa" if the passed-in argument points to a class A object, and "father" for a class B object , "son" for a class C object.

Your submitted source code should include the whole implementation of the function verify, but without any class defined above.
No main() function should be included.

主程序：

#include <iostream>  
#include <string>  
 
using namespace std;  
   
class A {  
public:  
     virtual ~A() {};  
 };  
 class B: public A {};   
 class C: public B {};   
   
 #include "source"  
   
 int main()  
 {  
     A a;  
     B b;  
     C c;  
     cout<<verify(&a)<<endl;  
     cout<<verify(&b)<<endl;  
     cout<<verify(&c)<<endl;  
   
     return 0;  
 }

答案程序 "source":

string verify(A *p)
{
  if (dynamic_cast<C*>(p))
     return "son";
  else if (dynamic_cast<B*>(p))
     return "father";
  else
     return "grandpa";
}