多态案例（3个）

目录

案例1：计算器类

案例2：制作饮品

案例3：电脑组装需求分析/具体实现

---

案例1：计算器类

普通写法：

#include<iostream>
using namespace std;
#include<string>

//分别利用普通写法和多态技术实现计算器

//普通写法
class Calculator
{
public:
	int getResult(string oper)
	{
		if (oper == "+")
		{
			return m_Num1 + m_Num2;
		}
		else if (oper == "-")
		{
			return m_Num1 - m_Num2;
		}
		else if (oper == "*")
		{
			return m_Num1 * m_Num2;
		}
	}

	int m_Num1;//操作数1
	int m_Num2;//操作数2
};

void test01()
{
	//创建一个计算器对象
	Calculator c;

	c.m_Num1 = 10;
	c.m_Num2 = 10;

	cout << c.m_Num1 << "+" << c.m_Num2 << "=" << c.getResult("+") << endl;
	cout << c.m_Num1 << "-" << c.m_Num2 << "=" << c.getResult("-") << endl;
	cout << c.m_Num1 << "*" << c.m_Num2 << "=" << c.getResult("*") << endl;
}

int main()
{
	test01();

	system("pause");
	return 0;
}

多态写法：

#include<iostream>
using namespace std;
#include<string>

//利用多态实现计算器

//实现计算器抽象类
class AbstractCalculator
{
public:
	virtual int getResult()
	{
		return 0;
	}
	int m_Num1;//操作数1
	int m_Num2;//操作数2
};

//加法计算器类
class AddCalculator :public AbstractCalculator
{
public:
	int getResult()
	{
		return m_Num1 + m_Num2;
	}
};
//减法计算器类
class SubCalculator :public AbstractCalculator
{
public:
	int getResult()
	{
		return m_Num1 - m_Num2;
	}
};
//乘法计算器类
class MulCalculator :public AbstractCalculator
{
public:
	int getResult()
	{
		return m_Num1 * m_Num2;
	}
};

void test01()
{
	//多态使用条件
	//父类指针或者引用指向子类对象
	AbstractCalculator *abc=new AddCalculator;

	abc->m_Num1 = 10;
	abc->m_Num2 = 10;

	cout << abc->m_Num1 << "+" << abc->m_Num2 << "=" << abc->getResult() << endl;
	delete abc;

	abc = new SubCalculator;
	abc->m_Num1 = 100;
	abc->m_Num2 = 100;
	cout << abc->m_Num1 << "-" << abc->m_Num2 << "=" << abc->getResult() << endl;
	delete abc;

	abc = new MulCalculator;
	abc->m_Num1 = 1000;
	abc->m_Num2 = 1000;
	cout << abc->m_Num1 << "*" << abc->m_Num2 << "=" << abc->getResult() << endl;
	delete abc;
}

int main()
{
	test01();

	system("pause");
	return 0;
}

案例2：制作饮品

#include<iostream>
using namespace std;
#include<string>


class AbstractDrinking
{
public:

	//煮水
	virtual void Boil() = 0;

	//冲泡
	virtual void Brew() = 0;

	//倒入杯中
	virtual void PourInCup() = 0;

	//加入辅料
	virtual void PutSomething() = 0;

	//制作饮品
	void makeDrink()
	{
		Boil();
		Brew();
		PourInCup();
		PutSomething();
	}

};

//制作咖啡
class Coffee :public AbstractDrinking
{
public:
	//煮水
	virtual void Boil()
	{
		cout << "煮水" << endl;
	}

	//冲泡
	virtual void Brew()
	{
		cout << "冲泡咖啡" << endl;
	}

	//倒入杯中
	virtual void PourInCup()
	{
		cout << "倒入杯中" << endl;
	}

	//加入辅料
	virtual void PutSomething()
	{
		cout << "加入糖和牛奶" << endl;
	}
};

//制作茶叶
class Tea :public AbstractDrinking
{
public:
	//煮水
	virtual void Boil()
	{
		cout << "煮矿泉水" << endl;
	}

	//冲泡
	virtual void Brew()
	{
		cout << "冲泡茶叶" << endl;
	}

	//倒入杯中
	virtual void PourInCup()
	{
		cout << "倒入茶杯中" << endl;
	}

	//加入辅料
	virtual void PutSomething()
	{
		cout << "加入柠檬、枸杞" << endl;
	}
};

void doWork(AbstractDrinking * abs)
{
	abs->makeDrink();
	delete abs;//释放
}
void test01()
{
	//制作咖啡
	doWork(new Coffee);

	cout << "----------------------------------" << endl;
	//制作茶叶
	doWork(new Tea);
}

int main()
{
	test01();

	system("pause");
	return 0;
}

案例3：电脑组装需求分析/具体实现

#include<iostream>
using namespace std;
#include<string>

//抽象不同零件类
//抽象CPU类
class CPU
{
public:
	//抽象及计算的函数
	virtual void calculate() = 0;
};

//抽象显卡类
class VideoCard
{
public:
	//抽象及计算的函数
	virtual void dispaly() = 0;
};

//抽象内存条类
class Memory
{
public:
	//抽象及计算的函数
	virtual void srorage() = 0;
};

//电脑类
class Computer
{
public:
	Computer(CPU* cpu, VideoCard* vc, Memory* mem)
	{
		m_cpu = cpu;
		m_vc = vc;
		m_mem = mem;

	}

	//提供工作的函数
	void work()
	{
		m_cpu->calculate();
		m_vc->dispaly();
		m_mem->srorage();
		//让零件工作起来，调用接口
	}

	//提供析构函数 释放3个电脑零件
	~Computer()
	{
		//释放CPU零件
		if (m_cpu != NULL)
		{
			delete m_cpu;
			m_cpu = NULL;
		}
		//释放显卡零件
		if (m_vc != NULL)
		{
			delete m_vc;
			m_vc = NULL;
		}
		//释放内存条零件
		if (m_mem != NULL)
		{
			delete m_mem;
			m_mem = NULL;
		}
	}

private:
	CPU* m_cpu;//CPU的零件指针
	VideoCard* m_vc;//显卡零件指针
	Memory* m_mem;//内存条的零件指针
};

//具体厂商
//Intel厂商
class IntelCPU :public CPU
{
public:
	virtual void calculate()
	{
		cout << "Intel 的CPU开始计算了" << endl;
	}
};

class IntelVideoCard :public VideoCard
{
public:
	virtual void dispaly()
	{
		cout << "Intel 的显卡开始显示了" << endl;
	}
};

class IntelMemory :public Memory
{
public:
	virtual void srorage()
	{
		cout << "Intel 的内存条开始存储了" << endl;
	}
};

//Lenovo厂商
class LenovoCPU :public CPU
{
public:
	virtual void calculate()
	{
		cout << "Lenovo 的CPU开始计算了" << endl;
	}
};

class LenovoVideoCard :public VideoCard
{
public:
	virtual void dispaly()
	{
		cout << "Lenovo 的显卡开始显示了" << endl;
	}
};

class LenovoMemory :public Memory
{
public:
	virtual void srorage()
	{
		cout << "Lenovo 的内存条开始存储了" << endl;
	}
};

void test01()
{
	//第一台电脑的零件
	CPU * intelCpu = new IntelCPU;//用父类的指针指向子类对象
	VideoCard* intelCard = new IntelVideoCard;
	Memory* intelMem = new IntelMemory;

	cout << "第一台电脑开始工作" << endl;
	//创建第一台电脑
	Computer * computer1 = new Computer(intelCpu, intelCard, intelMem);
	computer1->work();
	delete computer1;

	cout << "------------------------------" << endl;
	cout << "第二台电脑开始工作" << endl;
	//组装第二台电脑
	Computer* computer2 = new Computer(new LenovoCPU, new LenovoVideoCard, new LenovoMemory);
	computer2->work();
	delete computer2;

	cout << "------------------------------" << endl;
	cout << "第三台电脑开始工作" << endl;
	//组装第三台电脑
	Computer* computer3 = new Computer(new LenovoCPU, new IntelVideoCard, new LenovoMemory);
	computer3->work();
	delete computer3;
}

int main()
{
	test01();

	system("pause");
	return 0;
}