二义性：Common Base Class

// virtualbase.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include<iostream>
using namespace std;

class A
{
protected:
 int a;
public:
 A(int aa):a(aa)
 {}
 ~A(void)
 {}
};
class B:virtual public A
{
protected:
 int b;
public:
 B(int aa,int bb):A(aa),b(bb)
 {}
 ~B(void)
 {}
 
};
class BB:virtual public A
{
protected:
 int bb;
public:
 BB(int bbb,int aaa):bb(bbb),A(aaa)
 {}
 ~BB(void)
 {}

};
class C:public B,public BB
{
protected :
 int c;
public:
 C(int a,int b,int bb,int cc):B(a,b),BB(a,bb),c(cc),A(a)
 {}
 ~C(void)
 {}
 void showc()
 {
  cout<<a<<endl;
  cout<<b<<endl;
  cout<<c<<endl;
 }
};

int _tmain(int argc, _TCHAR* argv[])
{
 C cc(1,2,3,4);
 cc.showc();
 return 0;
 
}