1.子类重载父类public虚函数，并设置访问属性为private，多态仍然生效，可以访问子类虚函数，见下面func()
2.父类public成员，子类private继承后变成private，通过public下的using声明，可以重置为public，见下面成员a
#include <iostream>
#include <string>
#include <vector>
using namespace std;
class Base
{
public:
int a = 10;
virtual void func() { cout << "base func" << endl; } //虚函数,public
};
class Derived : public Base
{
private:
virtual void func() { cout << "derived func" << endl; } //虚函数重写,private
};
class Derived1 : private Base //私有继承,Base::a不可访问
{
private:
virtual void func() { cout << "derived func" << endl; }
public:
using Base::a; //重置Base::a访问属性为public
};
int main()
{
Base* pb = new Derived;
pb->func(); //调用Derived::fuc(),多态生效,跳过了Derived::fuc()函数private的限制
Derived1 d1;
cout << d1.a << endl;
return 0;
}