C++笔试常考题 虚函数

#include<iostream>
using namespace std;
class Base
{
public:
	virtual void f()
	{
		this->print(); //为什么此处其知道指向的是派生类对象而非派生类对象的基类部分
	}
	virtual void print(int i=6)
	{
		cout<<"Base:"<< i*i <<endl;
	}
};
class Derived : public Base
{
public:
	virtual void f()
	{
		this->print();  //
	}
	virtual void print(int i=10)
	{
		cout<<"Derived" << i*i<<endl;
	}
};
void bar(Base* p)
{
	p->print();
	p->f();
}


int main()
{
	Base * p = new Base;
	bar(p);
    Derived  * q = new Derived();
    bar(q);
	Base * r = (Base *)new Derived();
	bar(r);
	

	system("pause");
	return 0;
}

Base:36

Base:36
Derived36
Derived100
Derived36
Derived100
请按任意键继续. . .