virtual解决菱形继承中多份拷贝问题

我一直都知道菱形继承的时候，虚继承就能解决一个基类多份拷贝的问题。但是，已经忘了virtual应该添在哪里了，俗话说得好啊，好记性不如烂笔头，还是记下来吧。纯属笔记，读者请略过。

#include<iostream> using namespace std; class A { public: A(){ cout << "A()" << endl;} ~A(){ cout << "~A()" << endl;} }; class B: virtual public A { public: B(){ cout << "B()" << endl;} ~B(){ cout << "~B()" << endl;} }; class C:virtual public A { public: C(){ cout << "C()" << endl;} ~C(){ cout << "~C()" << endl;} }; class D: public B, C { public: D(){ cout << "D()" << endl;} ~D(){ cout << "~D()" << endl;} }; int main() { D d; return 0; }