JH

多态代码实例

计算器类

目的是为了说明运用多态抒写代码的好处

首先我们先用类写一个普通的

代码：

#include<iostream>
#include<iostream>
using namespace std;
//利用普通写法和多态来进行运算的计算器 

//1.普通写法 
class calculator
{
public:
	int function(string oper)
	{
		if(oper=="+")
		{
			return m_A+m_B;
		}
		else if(oper=="-")
		{
			return m_A-m_B;
		}
		else if(oper=="*")
		{
			return m_A*m_B;
		}
		else
		{
			if(m_B!=0)
			 return m_A/m_B;
		}
	}
public:
	int m_A;
	int m_B;
};

void test()
{
	calculator c; 
	c.m_A=20;
	c.m_B=15;
	cout<<"m_A+m_B= "<<c.function("+")<<endl;
	cout<<"m_A-m_B= "<<c.function("-")<<endl;
	cout<<"m_A*m_B= "<<c.function("*")<<endl;
	cout<<"m_A/m_B= "<<c.function("/")<<endl;
}
int main()
{
	test();
	system("pause");
	return 0;
	
} 

对于普通的代码，我们如果想修改某部分的内容的话，不是很方便，所以下面我们用多态来写

多态的好处：

1.可读性强

2.组织结构清晰

3.对于前期和后期扩展以及维护性高

多态代码：

#include<iostream>
#include<iostream>
using namespace std;
//多态写法

//计算器类 
class Calculator
{
public:
	virtual int GetResult()
	{
		
	} 
public:
	int m_A;
	int m_B;
};
//计算器加法子类
class AddCalculator:public Calculator
{
	int GetResult()
	{
		return m_A+m_B;
	}
};
//计算器减法子类
class  SubCalculator:public Calculator
{
	int GetResult()
	{
		return m_A-m_B;
	}
};
//计算器乘法子类
class MulCalculator:public Calculator
{
	int GetResult()
	{
		return m_A*m_B;
	}
};
//测试函数 
void test()
{
	//多态的使用条件：父类指针或者引用指向子类对象 
	Calculator *c=new AddCalculator;
	c->m_A=15;
	c->m_B=30;
	cout<<"m_A+m_B= "<<c->GetResult()<<endl;
	delete c; 
	
	c=new SubCalculator;
	c->m_A=15;
	c->m_B=30;
	cout<<"m_A-m_B= "<<c->GetResult()<<endl;
	delete c; 
	
	c=new MulCalculator;
	c->m_A=15;
	c->m_B=30;
	cout<<"m_A*m_B= "<<c->GetResult()<<endl;
	delete c; 
}
int main()
{
	test();
	system("pause");
	return 0;
	
} 

制作饮品类

代码：

#include<iostream>
#include<string.h>
using namespace std;
//多态案例2-制作饮料 
class AbstractDrinking 
{
public:
	//煮水
	virtual void Boid()=0;
	//冲泡
	virtual void Brew()=0;
	//倒入杯中
	virtual void PourInCup()=0;
	//加入辅料
	virtual void PutSomething()=0;
	//制作饮料
    void MakeDrink()
	{
		Boid();
		Brew();
		PourInCup();
		PutSomething();
	}
};
//子类1 制作咖啡 
class Coffe:public AbstractDrinking
{
	//煮水
	virtual void Boid()
	{
		cout<<"烧开水"<<endl;
	}
	//冲泡
	virtual void Brew()
	{
		cout<<"冲泡咖啡"<<endl;
	}
	//倒入杯中
	virtual void PourInCup()
	{
		cout<<"咖啡倒入杯中"<<endl; 
	}
	//加入辅料
	virtual void PutSomething()
	{
		cout<<"加入红糖"<<endl;
	}
};

//子类2 制作咖啡 
class Tea:public AbstractDrinking
{
	//煮水
	virtual void Boid()
	{
		cout<<"烧开水"<<endl;
	}
	//冲泡
	virtual void Brew()
	{
		cout<<"冲泡茶叶"<<endl;
	}
	//倒入杯中
	virtual void PourInCup()
	{
		cout<<"茶叶倒入杯中"<<endl; 
	}
	//加入辅料
	virtual void PutSomething()
	{
		cout<<"加入柠檬"<<endl;
	}
};
void DoWork(AbstractDrinking *abc)
{
	abc->MakeDrink();
	delete abc;       //对堆区开辟数据进行释放 
} 
void test()
{
	DoWork(new Tea);
	cout<<"--------------------"<<endl;
	DoWork(new Coffe);
}
int main()
{
	test();
	system("pause");
	return 0;
}

电脑类

代码：

#include<iostream>
#include<string.h>
using namespace std;
//抽象出每个零件的类 

class CPU
{
public:
	//抽象计算函数
	virtual void Calculate()=0; //纯虚函数 
};
class VideoCard
{
public:
	//抽象显示函数
	virtual void Display()=0;  //纯虚函数 
};
class Memory
{
public:
	//抽象存储函数
	virtual void Storage()=0;  //纯虚函数 
};

//抽象电脑类
class Computer
{
public:
	Computer(CPU *cpu,VideoCard *vc,Memory *mem)
	{
		m_cpu=cpu;
		m_vc=vc;
		m_mem=mem;
	}
	//工作函数 
	void DoWork()
	{
		//通过变量定义来调用 
		m_cpu->Calculate();
		m_vc->Display();
		m_mem->Storage(); 
	}
	//析构函数
	~Computer()
	{
		if(m_cpu!=NULL)
		{
			delete m_cpu;
			m_cpu=NULL;
		}
			if(m_vc!=NULL)
		{
			delete m_vc;
			m_vc=NULL;
		}
		if(m_mem!=NULL)
		{
			delete m_mem;
			m_mem=NULL;
		}
	} 
private:
	CPU *m_cpu;
	VideoCard *m_vc;
	Memory *m_mem;
};

//具体厂商生产
//inter
class InterCpu:public CPU
{
public:
	virtual void Calculate()
	{
		cout<<"Inter的CPU开始计算！！！"<<endl;
	}
}; 
class InterVideoCard:public VideoCard
{
public:
	virtual void Display()
	{
		cout<<"Inter的Card开始显示！！！"<<endl;
	}
}; 
class InterMemory:public Memory
{
public:
	virtual void Storage()
	{
		cout<<"Inter的mem开始储存！！！"<<endl;
	}
}; 

//lenovo
class LenovoCpu:public CPU
{
public:
	virtual void Calculate()
	{
		cout<<"Lenovo的CPU开始计算！！！"<<endl;
	}
}; 
class LenovoVideoCard:public VideoCard
{
public:
	virtual void Display()
	{
		cout<<"Lenovo的Card开始显示！！！"<<endl;
	}
}; 
class LenovoMemory:public Memory
{
public:
	virtual void Storage()
	{
		cout<<"Lenovo的mem开始储存！！！"<<endl;
	}
}; 
//Inter电脑 
void test1()
{
	//创建第一台电脑零件
	CPU *intercpu=new InterCpu;
	VideoCard *intercard=new InterVideoCard;
	Memory *intermem=new InterMemory;
	//创建第一台电脑
	Computer *computer1=new Computer(intercpu,intercard,intermem);
	computer1->DoWork();
	delete computer1;
}
//Lenovo电脑 
void test2()
{
	//第二台电脑
	CPU *lenovocpu=new LenovoCpu;
	VideoCard *lenovocard=new LenovoVideoCard;
	Memory *lenovomem=new LenovoMemory;
	
	Computer *computer2=new Computer(lenovocpu,lenovocard,lenovomem);
	computer2->DoWork();
	delete computer2;
}
//二者组合电脑
void test3()
{
	CPU *intercpu=new InterCpu;
	VideoCard *lenovocard=new LenovoVideoCard;
	Memory *lenovomem=new LenovoMemory;
	
	Computer *computer2=new Computer(intercpu,lenovocard,lenovomem);
	computer2->DoWork();
	delete computer2;
}
int main()
{
	//test1();
	//test2();
	test3();
	system("pause");
	return 0;
}

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