虚拟继承中子类和父类的构造函数顺序1

class A{
protected://不能写private
	int a;
public:
	A(int x) :a(x){}
};

class B:virtual public A
{

public:
	B(int x) :A(x){}
};

class C :virtual public A
{
public:
	C(int x) :A(x){}
	void display()
	{
		cout << a << endl;//这个A的数据可以在这里使用
	}
};

class D :public B, public C
{
private:
	int d;
public:
	D(int x, int y) :B(x), C(x), d(y),A(x){}//这个A（x）一定要写
	void display()
	{
		cout << a << endl << d << endl;
	}
};

int main()
{
	C c(1);
	c.display();
	D d(1, 2);
	d.display();
}