C++ dynamic_cast用法

示例example

class B

{

virtual void f(){};

};

class D : public B

{

virtual void f(){};

};

int main(void)

{

 B* pb = new D; // unclear but ok

 B* pb2 = new B; 

 D* pd = dynamic_cast(pb); // ok: pb actually points to a D 

 D* pd2 = dynamic_cast(pb2); // pb2 points to a B not a D, now pd2 is NULL

return 0;

}

父类向子类转化，需要在开始的时候事先实例化子类！