多重继承的虚函数表

Father类:

class Father {
public:
	virtual void Func1() { cout << "Father::Func1" << endl; }
	virtual void Func2() { cout << "Father::Func2" << endl; }
	virtual void Func3() { cout << "Father::Func3" << endl; }
	void Func4() { cout << "Father::Func4" << endl; }
public:
	int x = 200;
	int y = 300;
	static int z;
};
int Father::z = 0;

Mather类:

class Mather {
public:
	virtual void Handle1() { cout << "Mother::Handle1" << endl; }
	virtual void Handle2() { cout << "Mother::Handle2" << endl; }
	virtual void Handle3() { cout << "Mother::Handle3" << endl; }
public:
	int i = 600;
	int j = 800;
};

Son类: public Father,public Mather

class Son:public Father,public Mather
{
public:
	void Func1() { cout << "Son::Func1" << endl; }//重写Father类的Func1();
	void Handle1() { cout << "Son::Handle1" << endl; }//重写Mather类的Handle1();
	virtual void Func5() { cout << "Son::Func5" << endl; }//自己新添加的虚函数
};

Son的内存分析:

注意:自己新添加的虚函数添加到第一个虚函数表中,其他重写的函数则直接在对应的虚函数表中进行替换. 

此处Son类的基类为Father类和Mather类,则第一个虚函数表为Father继承下来的虚函数表,Monther类继承下来的虚函数表为第二虚函数表,所以Son类新添加的虚函数添加到第一个虚函数表中.

完整代码:

#include
using namespace std;
//vs的对象内存分析：/d1 reportSingleClassLayout+类名
class Father {
public:
	virtual void Func1() { cout << "Father::Func1" << endl; }
	virtual void Func2() { cout << "Father::Func2" << endl; }
	virtual void Func3() { cout << "Father::Func3" << endl; }
	void Func4() { cout << "Father::Func4" << endl; }
public:
	int x = 200;
	int y = 300;
	static int z;
};
int Father::z = 0;

class Mather {
public:
	virtual void Handle1() { cout << "Mother::Handle1" << endl; }
	virtual void Handle2() { cout << "Mother::Handle2" << endl; }
	virtual void Handle3() { cout << "Mother::Handle3" << endl; }
public:
	int i = 600;
	int j = 800;
};

class Son:public Father,public Mather
{
public:
	void Func1() { cout << "Son::Func1" << endl; }//重写Father类的Func1();
	void Handle1() { cout << "Son::Handle1" << endl; }//重写Mather类的Handle1();
	virtual void Func5() { cout << "Son::Func5" << endl; }//自己新添加的虚函数
};

typedef void(*func)(void);

int main(void) {
	
	Son son;
	int* vptr =(int*)*(int*)&son;
	cout << "sizeof(son):" << sizeof(son) << endl;
	cout << "第一个虚函数表指针" << vptr << endl;
	for (int i = 0; i < 4; i++) {
		cout << "调用第" << i + 1 << "个虚函数:";
		((func) * (vptr + i))();
	}
	for (int i = 0; i < 2; i++) {
		cout << *(int*)((int)&son + 4 + i * 4) << endl;
	}
	int* vptr2 = (int*)*(int*)((int)&son + 12);
	//int* vptr2 = (int*)*((int*)&son + 3);//结果一样
	cout << "第二个虚函数表指针" << vptr2 << endl;
	for (int i = 0; i < 3; i++) {
		cout << "调用第" << i + 1 << "个虚函数:";
		((func) * (vptr2 + i))();
	}
	for (int i = 0; i < 2; i++) {
		cout << *(int*)((int)&son + 16 + i * 4) << endl;
	}
	return 0;
}

运行结果: