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策略模式

前序

请实现一个商场收银软件,包含正常收费,打折收费和返利收费三种具体策略

策略模式

策略模式定义了一系列的算法,并将每一个算法封装起来,而且使它们还可以相互替换。策略模式让算法独立于使用它的客户而独立变化。

实现方式(UML类图)

实现代码

#include <stdio.h>

 

class CashSuper

{

public:

       virtual double acceptCash(double money)=0;

};

 

class CashNormal : public CashSuper

{

public:

       virtual double acceptCash(double money)

       {

              return money;

       }

};

 

class CashRebate : public CashSuper

{

protected:

       double moneyRebate;

public:

       CashRebate() : moneyRebate(1){}

       CashRebate(double _moneyRebate) : moneyRebate(_moneyRebate){}

 

       virtual double acceptCash(double money)

       {

              return money * moneyRebate;

       }

};

 

class CashReturn : public CashSuper

{

protected:

       double moneyCondition;

       double moneyReturn;

public:

       CashReturn() : moneyCondition(0),moneyReturn(0){}

       CashReturn(double _moneyCondition,double _moneyReturn)

              : moneyCondition(_moneyCondition),moneyReturn(_moneyReturn)

       {}

 

       virtual double acceptCash(double money)

       {

              double result = money;

              if(money >= moneyCondition) result -= (int)(money / moneyCondition) * moneyReturn;

              return result;

       }

};

 

class CashContext

{

protected:

       CashSuper* cs;

public:

       CashContext() : cs(0){}

       ~CashContext()

       {

              if(cs) delete cs;

       }

 

       CashContext& operator=(CashSuper* csuper)

       {

              if(cs) delete cs;

              cs = csuper;

              return *this;

       }

 

       double GetResult(double money)

       {

              return cs->acceptCash(money);

       }

};

 

int main()

{

       double total = 0;

       int Type;

       while(1)

       {

              printf("请输入收费方式(0~2,-1退出):");

              scanf("%d",&Type);

              if(Type == -1) break;

              CashContext cc;

              switch(Type)

              {

              case 0:

                     cc = new CashNormal();

                     break;

              case 1:

                     cc = new CashReturn(300,100);

                     break;

              case 2:

                     cc = new CashRebate(0.8);

                     break;

              default:

                     cc = new CashNormal();

                     break;

              }

              double Price,Num;

              printf("请输入单价:");

              scanf("%lf",&Price);

              printf("请输入数量:");

              scanf("%lf",&Num);

              total += cc.GetResult(Price * Num);

       }

       printf("总价:%f\n",total);

       return 0;

}

运行结果


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posted on 2011-05-04 15:10 lwch 阅读(1338) 评论(0)  编辑 收藏 引用 所属分类: 设计模式

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