程序小白天天打卡

2018/2/4

虚方法（virtual way）

 1.在以前访问变量的时候，是先建立变量，再将变量的地址赋给了指针，通过指针来访问变量的值

Pig pig1("八戒");
	Turtle turtle1("龟龟");
	cout << "猪类" << endl;
	cout << "这只猪的名字是" << pig1.name << endl;
	pig1.eat();
	/*方法的重载*/
	pig1.eatcount(15);
	pig1.drool();
	pig1.sleep();
	pig1.climb();
	cout << "龟类" << endl;
	cout << "这只龟的名字是" << endl;
	turtle1.eat();
	turtle1.drool();
	turtle1.sleep();
	turtle1.swim();

2.现在可以采用虚方法，（new delete）直接创建某个指针指向新分配的内存块

{
	/*使用虚方法new delete 直接建立指针指向分配内存区*/
	Animal *pig = new Pig("八戒");
	Animal *turtle = new Turtle("龟龟");
	cout << "这只猪的名字是" << pig->name << endl;
	pig->eatcount(15);
	
	pig->drool();
	pig->sleep();
	pig->eat();
	pig->climb();
	cout << "这只龟的名字是" <<turtle->name <<endl;
	turtle->drool();
	turtle->sleep();
	turtle->swim();
	turtle->eat();
	/*！！删除指针！！*/
	delete pig;
	delete turtle;

注意

 1.使用虚方法时，要注意创建指针后，一定要用delete来删除指针

 2.由于C++的编译器采用最优读取代码的原则，所以使用方法的重载和覆盖时，要注意使用visual前缀来使编译器正常编译

/*虚方法*/
/*visual way*/
/*以前访问变量时，是先创建一个变量，变量的地址赋给指着你，可以访问变量所在的位置
采用虚方法（new delete）可以直接创建指针来访问新分配的内存块
	注意:
		1.使用new创建指针后必须要用delete来删除指针；
		2.由于编译器的特殊性，喜欢找最优的编译方式，所以使用虚方法时，对于重载或覆盖的方法要用visual前缀*/
#include<iostream>
#include<stdlib.h>
#include<string>

using namespace std;
class Animal
{
public:
	string name;
	virtual void eat();
	virtual void climb();
	/*方法的重载*/
	void eatcount(int num);
	void sleep();
	void drool();
protected:
	Animal(string theName);

};
class Pig :public Animal
{
public:
	Pig(string theName);
	void eat();
	void climb();
};
class Turtle :public Animal
{
public:
	void swim();
	Turtle(string theName);
	void eat();

};
Animal::Animal(string theName)
{
	name = theName;
}
void Animal::climb()
{
	cout << "I am climbing" << endl;
}
void Animal::eat()
{
	cout << "I am eatting" << endl;
}
void Animal::sleep()
{
	cout << "I am sleeping，Don`t bother me" << endl;
}
void Animal::drool()
{
	cout << "HUA HUA HUA。。。。" << endl;
}
void Animal::eatcount(int num)
{
	cout << "我吃了" << num << "碗饭" << endl;
}
/*启用猪类构造器*/
Pig::Pig(string theName) :Animal(theName)
{
}
/*方法的覆盖
相当于在子类中重新定义一个方法，该方法继承于基类的方法（Animal::eat()）,注意要在子类中重新声明方法*/
void Pig::eat()
{
	/*Animal::eat();*/
	cout << "I am eatting the meat" << endl;


}
void Pig::climb()
{
	cout << "母猪会上树\n" << endl;
}
/*继承构造器*/
Turtle::Turtle(string TheName) :Animal(TheName)
{
}
void Turtle::swim()
{
	cout << "总有一天我会超越孙杨\n" << endl;

}
void Turtle::eat()
{
	/*	Animal::eat();*/
	/*方法的覆盖*/
	cout << "我要吃鱼" << endl;
}
void main()
{
	/*使用虚方法new delete 直接建立指针指向分配内存区*/
	Animal *pig = new Pig("八戒");
	Turtle *turtle = new Turtle("龟龟");
	cout << "这只猪的名字是" << pig->name << endl;
	pig->eatcount(15);
	
	pig->drool();
	pig->sleep();
	pig->eat();
	pig->climb();
	cout << "这只龟的名字是" <<turtle->name <<endl;
	turtle->drool();
	turtle->sleep();
	turtle->swim();
	turtle->eat();
	/*！！删除指针！！*/
	delete pig;
	delete turtle;
	system("pause");





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