C++虚函数表地址偏移

#include <bits/stdc++.h>
using namespace std;

class Base {
public:
	Base() {
		cout << "Base构造" << endl;
	}
	virtual ~Base() {
		cout << "Base虚析构" << endl;
	}
	virtual void f1() {
		cout << "Base::f1()" << endl;
	}
	void f2() {
		cout << "Base::f2()" << endl;
	}
	virtual void f3() {
		cout << "Base::f3()" << endl;
		//cout << data << endl;	
	}
	int data = 5;
	static void fn() {
	}
};

int main() {
	cout << sizeof(Base) << endl;

	Base* p1 = new Base();
	Base* p2 = new Base();
	cout << p1->fn << endl;		// 静态成员函数可以直接获取地址
	cout << Base::fn << endl;	// 静态成员函数可以直接获取地址

//	cout << &Base::f1 << endl;	// 编译器将void(__thiscall A::*)()类型转换为bool类型
	printf("Base::f1()地址:%p\n", &Base::f1);
	printf("Base::f1()地址:%p\n", &Base::f1);
	printf("Base::f2()地址:%p\n", &Base::f2);
	printf("Base::fn()地址:%p\n", &Base::fn);

	cout << "p1对象地址: " << (p1) << endl;
	cout << "p1虚函数表首地址: " << (int*)(p1) << endl;
	cout << "p1虚函数表中第1个虚函数地址: " << (int*)*(int*)(p1) << endl;
	cout << "p1虚函数表中第2个虚函数地址: " << ((int*)*(int*)(p1)+1) << endl;
	cout << "p1虚函数表中第3个虚函数地址: " << ((int*)*(int*)(p1)+2) << endl;
	cout << "p1虚函数表中第4个虚函数地址: " << ((int*)*(int*)(p1)+3) << endl;


	cout << "p2对象地址: " << (p2) << endl;
	cout << "p2虚函数表首地址: " << (int*)(p2) << endl;
	cout << "p2虚函数表中第1个虚函数地址: " << (int*)*(int*)(p2) << endl;
	cout << "p2虚函数表中第2个虚函数地址: " << ((int*)*(int*)(p2)+1) << endl;
	cout << "p2虚函数表中第3个虚函数地址: " << ((int*)*(int*)(p2)+2) << endl;
	cout << "p2虚函数表中第4个虚函数地址: " << ((int*)*(int*)(p2)+3) << endl;

	cout << endl;

	typedef void(*PFUN)();

	PFUN pfBase = (PFUN) * ((int*)*(int*)p1 + 0);	// 析构
	PFUN pf1 = (PFUN) * ((int*)*(int*)p1 + 1);	// f1
	PFUN pf2 = (PFUN) * ((int*)*(int*)p1 + 2);	// f2
	PFUN pfnull = (PFUN) * ((int*)*(int*)p1 + 3);	//0x00
	pf1();
	pf2();	// 如果函数中有类成员变量，这样调用会出错。普通变量不会。和this指针有关。

}

C/C++获取函数地址