策略模式 + 简单工厂模式

//cash.h
#ifndef _CASH_H_
#define _CASH_H_

#include <string>
using namespace std;

class CashSuper
{
    public:
        CashSuper() {}
        virtual ~CashSuper() {}
        virtual double acceptCash(double money) {}
    
};

class CashNormal: public CashSuper
{
    public:
        double acceptCash(double money);
};

class CashReturn: public CashSuper
{
    public:
        CashReturn(double condition = 0.0, double re = 0.0):moneyCondition(condition), moneyReturn(re) {}
        ~CashReturn() {}
        double acceptCash(double money);
    private:
        double moneyCondition;
        double moneyReturn;
};

class CashRebate: public CashSuper
{
    public:
        CashRebate(double rate = 1.0): cashRate(rate) {}
        ~CashRebate() {}
        double acceptCash(double money);
    private:
        double cashRate;
};

class CashContext
{
    public:
        CashContext(const string &type);
        ~CashContext();
        double getResult(double money);
        void setType(const string &type);
    private:
        void setCash(const string &type);
        CashSuper *cs;
};

CashContext::CashContext(const string &type):cs(NULL)
{
    this->setCash(type);
}

CashContext::~CashContext()
{
    if(cs != NULL)
    {
        delete cs;
        cs = NULL;
    }
}

void CashContext::setType(const string &type)
{
    this->setCash(type);
}

void CashContext::setCash(const string &type)
{
    if(type.compare("Normal") == 0)
        cs = new CashNormal();
    else if(type.compare("Return") == 0)
        cs = new CashReturn(300.0, 100.0);
    else if(type.compare("Rebate") == 0)
        cs = new CashRebate(0.8);
    else
        cs = NULL;
}

double CashContext::getResult(double money)
{
    if(cs != NULL)
        return cs->acceptCash(money);
    return 0;
}

double CashNormal::acceptCash(double money)
{
    return money;
}

double CashReturn::acceptCash(double money)
{
    double result = money;
    if(result >= this->moneyCondition && this->moneyCondition > 0)
        result -= (double)((int) (result / this->moneyCondition)) * this->moneyReturn;
    return result;
}

double CashRebate::acceptCash(double money)
{
    return money * cashRate;
}
#endif

#include <iostream>
#include <cstdio>
#include <string>
#include "cash.h"

using namespace std;

int main()
{
   
    string type1("Normal");
    string type2("Return");
    string type3("Rebate");
    double price = 80;
    int num = 10;

    CashContext context(type1);
    printf("The total money is: %.2lf\n", price * num);
    printf("Noraml strategy: %.2lf\n", context.getResult(price * num));
    context.setType(type2);
    printf("Return strategy: %.2lf\n", context.getResult(price * num));
    context.setType(type3);
    printf("Rebate strategy: %.2lf\n", context.getResult(price * num));
  
    return 0;
}