在基类中公有，子类私有继承，main()中不能被访问

源程序： 

#include <iostream>
using namespace std;class Base
{
private:
  int x;
public:
  Base(int a)
  {
    x=a;
  }
  int getX()
  {
    return x;
  }
  void show()
  {
    cout<<x<<endl;
  }
};class Derived:private Base
{
private:
  int y;
public:
  Derived(int b):Base(b)
  {
    y=b;
  }
  void show()
  {
    cout<<y<<endl;
  }
};int main()
{
  Base b(10);
  cout<<b.getX()<<endl;
  Derived d(20);
  cout<<d.Base::getX()<<endl;  //在基类中公有，但是子类私有继承，即getX()在子类中是私有的,类之外的main()中不能被访问 return 1;
}