C++之重载 重定义与重写用法详解

#include<iostream>
using namespace std;
class Base
{
public:
	void fun()
	{
		cout << "Base::fun()" << endl;
	}
	void fun(int a)
	{
		cout << "Base::fun(int)" << endl;
	}
	void fun(int a, float b)
	{
		cout << "Base::fun(int,float)" << endl;
	}
};
void main()
{
	Base c;
	c.fun();
	c.fun(1);
	c.fun(1, 1.0);
}

class Base
{
public:
	void fun()
	{
		cout << "Base::fun()" << endl;
	}
};
class D :public Base
{
public:
	void fun(int)
	{
		cout << "D fun(int)" << endl;
	}
};
int main()
{
	D d;
	//d.fun() 如果这样调用 系统会提示缺少参数
	d.fun(1);//同名隐藏，此时调用的是子类中的fun函数
	//如果想调用父类对象，下面的语句可以帮你实现，你需要指出调用的是谁的fun
	d.Base::fun();
	
}

class Person
{
public:
	virtual void Eat()
	{
		cout << "Person Eat food" << endl;
	}
	virtual void sleep()
	{
		cout << "Person sleep " << endl;
	}
	void study()
	{
		cout << "We need study" << endl;
	}
};
class Lily:public Person
{
public:
	virtual void Eat()
	{
		cout << "Lily Eat dumpling" << endl;
	}
	virtual void sleep()
	{
		cout << "Lily sleeps and dreams " << endl;
	}
};
void main()
{
	Lily L;
	/*子类对象不能直接调用被重写的方法
	因为对D实例化的对象来说重写的函数覆盖掉了父类的虚函数
	*/
	Person *pr = &L;
	pr->Eat();
	pr->sleep();
	L.study();
}