类型强转的那些坑

#include <iostream>
#include <Windows.h>
using namespace std;

class base
{
public:
	virtual void f() { cout << "Base::f" << endl; }
	int type;
};

class Derive :public base
{
public:
	 Derive(){type = 1;}
	void f() { cout << "Derive::f" << endl; }
	void f1() { cout << "Derive::f1" << endl; }
	int type;
};

class Derive2 :public base
{
public:
	Derive2(){type = 2;}
	void f() { cout << "Derive2::f" << endl; }
	void f2() { cout << "Derive2::f2" << endl; }
	int type;
};

void main()
{
	base *b = new Derive();
	/*
	Derive2* pb = (Derive2*)b;
	pb->f2();			//如果二个子类是很复杂的，很多时候这里就会报错 
	*/
	if(b->type == 2)	//正确的使用方式应该判断一下子类的原始类型
	{
		Derive2* pb = (Derive2*)b;
		pb->f2();	
	}
	system("pause");
}