大话设计模式：简单工厂模式

#include <iostream>  
using namespace std;  

//抽象产品类  
class Operation  
{  
protected:  
	double numberA;  
	double numberB;  

public:  
	double getA()  
	{  
		return numberA;  
	}  
	double getB()  
	{  
		return numberB;  
	}  
	void setA(double number)  
	{  
		numberA=number;  
	}  
	void setB(double number)  
	{  
		numberB=number;  
	}  

	virtual double GetResult()  
	{  
		double result=0;  
		return result;  
	}  
};  

//下面是四种具体产品类,只能是同一类的产品；
class OperationAdd:public Operation  
{  
public:  
	double GetResult()  
	{  
		double result=0;  
		result=numberA+numberB;  
		return result;  
	}  
};  

class OperationSub:public Operation  
{  
public:  
	double GetResult()  
	{  
		double result=0;  
		result=numberA-numberB;  
		return result;  
	}  
};  

class OperationMul:public Operation  
{  
public:  
	double GetResult()  
	{  
		double result=0;  
		result=numberA*numberB;  
		return result;  
	}  
};  

class OperationDiv:public Operation  
{  
public:  
	double GetResult()  
	{  
		double result=0;  
		if(numberB!=0)  
			result=numberA/numberB;  
		return result;  
	}  
};  

//工厂类,决定实例化那个产品；  
class OperationFactory  
{  
public:  
	Operation* createOperation(char type)  
	{  
		Operation* oper;  
		switch(type)  
		{  
		case '+':  
			oper=new OperationAdd;  
			break;  
		case '-':  
			oper=new OperationSub;  
			break;  
		case '*':  
			oper=new OperationMul;  
			break;  
		case '/':  
			oper=new OperationDiv;  
			break;  
		}  
		return oper;  
	}  
};  

//客户端  
int main()  
{  
	Operation* oper=NULL;  

	OperationFactory of;  
	oper=of.createOperation('+');  
	oper->setA(3);  
	oper->setB(2);  
	cout<<oper->GetResult()<<endl;  
	if(oper!=NULL)  
	{  
		delete oper;  
		oper=NULL;  
	}  

	system("pause");  
	return 0;
}  

运行结果：

大话设计模式：简单工厂模式

原文：http://blog.csdn.net/gogokongyin/article/details/51924764