#include <iostream>
using namespace std;

class Base
{
public :
	int base_data;
	Base() { base_data = 1; }
	virtual void func1() { cout << "base_func1" << endl; }
	virtual void func2() { cout << "base_func2" << endl; }
	virtual void func3() { cout << "base_func3" << endl; }
};

class Derive : public Base
{
public :
	int derive_data;
	Derive() { derive_data = 2; }
	virtual void func1() { cout << "derive_func1" << endl; }
	virtual void func2() { cout << "derive_func2" << endl; }
};

typedef void (*func)();

int main()
{
	Base base;
	cout << "&base: " << &base << endl;
	cout << "&base.base_data: " << &base.base_data << endl;
	cout << "----------------------------------------" << endl;

	Derive derive;
	cout << "&derive: " << &derive << endl;
	cout << "&derive.base_data: " << &derive.base_data << endl;
	cout << "&derive.derive_data: " << &derive.derive_data << endl;
	cout << "----------------------------------------" << endl;

	for(int i=0; i<3; i++)
	{
		// &base : base首地址
		// (unsigned long*)&base : base的首地址，vptr的地址
		// (*(unsigned long*)&base) : vptr的內容，即vtable的地址，指向第一個虛擬函式的slot的地址
		// (unsigned long*)(*(unsigned long*)&base) : vtable的地址，指向第一個虛擬函式的slot的地址
		// vtbl : 指向虛擬函式slot的地址
		// *vtbl : 虛擬函式的地址
		unsigned long* vtbl = (unsigned long*)(*(unsigned long*)&base) + i;
		cout << "slot address: " << vtbl << endl;
		cout << "func address: " << *vtbl << endl;
		func pfunc = (func)*(vtbl);
		pfunc();
	}	
	cout << "----------------------------------------" << endl;

	for(i=0; i<3; i++)
	{
		unsigned long* vtbl = (unsigned long*)(*(unsigned long*)&derive) + i;
		cout << "slot address: " << vtbl << endl;
		cout << "func address: " << *vtbl << endl;
		func pfunc = (func)*(vtbl);
		pfunc();
	}	
	cout << "----------------------------------------" << endl;
	return 1;
}