c++ virtual inheritance

[shihyuyao]

#include <iostream>
using namespace std;

class Uninheritable {
    friend class NotABase;
private:
    Uninheritable(void) {cout << "Uninheritable" << endl;}
};

class NotABase: public virtual Uninheritable {
};

class NotADerived: public NotABase {
};

int main(int argc, char *argv)
{

    NotADerived a;
    
    return 0;
}

class NotABase: public virtual Uninheritable
class NotABase: public Uninheritable

请问这代码加上 virtual 跟不加上 virtual , NotADerived a;对象内存是怎样？

谢谢

[hooked]

没有virtual 1> class NotADerived size(1): 1> +--- 1> | +--- (base class NotABase) 1> | | +--- (base class Uninheritable) 1> | | +--- 1> | +--- 1> +--- 有virtual 1> class NotADerived size(4): 1> +--- 1> | +--- (base class NotABase) 1> 0 | | {vbptr} 1> | +--- 1> +--- 1> +--- (virtual base Uninheritable) 1> +--- 1> 1> NotADerived::$vbtable@: 1> 0 | 0 1> 1 | 4 (NotADerivedd(NotABase+0)Uninheritable) 1> 1> 1> vbi: class offset o.vbptr o.vbte fVtorDisp 1> Uninheritable 4 0 4 0 http://blog.csdn.net/hooked/article/details/3440559