C++类之虚函数表和虚基类表及其内存布局（一个子类虚继承一个父类）

#include<iostream>
class B
{
public:
	int b;

public:
	B(int i = 1) : b(i) {}
	virtual void f() { std::cout << "B::f()"; }
	virtual void Bf() { std::cout << "B::Bf()"; }
};

class B1 : virtual public B
{
public:
	int b1;

public:
	B1(int i = 100) :b1(i) {}
	virtual void f() { std::cout << "B1::f()"; }
	virtual void f1() { std::cout << "B1::f1()"; }
	virtual void B1f() { std::cout << "B1::B1f()"; }
};
int main()
{
	B1 a;
	std::cout << "B1对象内存大小为：" << sizeof(a) << std::endl;

	//取得B1的虚函数表
	std::cout << "[0]B1::vptr";
	std::cout << "\t地址：" << (int *)(&a) << std::endl;
	
	typedef void(*Fun)(void);

	//输出虚表B1::vptr中的函数
	for (int i = 0; i < 2; ++i)
	{
		std::cout << "  [" << i << "]";
		Fun fun1 = (Fun)*((int *)*(int *)(&a) + i);
		fun1();
		std::cout << "\t地址：" << *((int *)*(int *)(&a) + i) << std::endl;
	}

	//[1]
	std::cout << "[1]vbptr ";
	std::cout << "\t地址：" << (int *)(&a) + 1 << std::endl;  //虚表指针的地址
												 //输出虚基类指针条目所指的内容
	for (int i = 0; i < 2; i++)
	{
		std::cout << "  [" << i << "]";

		std::cout << *(int *)((int *)*((int *)(&a) + 1) + i);

		std::cout << std::endl;
	}


	//[2]
	std::cout << "[2]B1::ib1=" << *(int*)((int *)(&a) + 2);
	std::cout << "\t地址：" << (int *)(&a) + 2;
	std::cout << std::endl;

	//[3]
	std::cout << "[3]值=" << *(int*)((int *)(&a) + 3);
	std::cout << "\t\t地址：" << (int *)(&a) + 3;
	std::cout << std::endl;

	//[4]
	std::cout << "[4]B::vptr";
	std::cout << "\t地址：" << (int *)(&a) + 4 << std::endl;

	//输出B::vptr中的虚函数
	for (int i = 0; i < 2; ++i)
	{
		std::cout << "  [" << i << "]";
		Fun fun1 = (Fun)*((int *)*((int *)(&a) + 4) + i);
		fun1();
		std::cout << "\t地址：" << *((int *)*((int *)(&a) + 4) + i) << std::endl;
	}

	//[5]
	std::cout << "[5]B::ib=" << *(int*)((int *)(&a) + 5);
	std::cout << "\t地址：" << (int *)(&a) + 5;
	std::cout << std::endl;
}

验证结果：

参考文章
图说C++对象模型：对象内存布局详解