虚函数注意点：参数

#include <iostream>
using namespace std;

class A
{
public:
virtual void Fun(int number = 10)
{
std::cout << "A::Fun with number " << number<<endl;
}
};

class B: public A
{
public:
virtual void Fun(int number = 20)
{
std::cout << "B::Fun with number " << number<<endl;
}
};

int main()
{
B b;
A &a = b;
a.Fun();
return 0;//输出结果10
}