大话设计模式

工厂模式和策略模式相结合

#include <iostream>
#include <math.h>

enum type{cashnormal, cashrebate, cashreturn};
typedef type CashType;

// 收费抽象类
class CashSuper
{
public:
    virtual double acceptCash(double money){};
};

// 正常收费子类
class CashNormal : public CashSuper
{
public:
    inline double acceptCash(double money)
    {
        return money;
    }
};

// 打折收费子类
class CashRebate : public CashSuper
{
public:
    CashRebate() = default;
    CashRebate(double moneyRebate);
    inline double acceptCash(double money)
    {
        return moneyRebate_ * money;
    }

private:
    double moneyRebate_;
};

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

// 返利收费子类
class CashReturn : public CashSuper
{
public:
    CashReturn() = default;
    CashReturn(double moneyCondition, double moneyReturn);
    double acceptCash(double money);

private:
    double moneyCondition_;
    double moneyReturn_;
};

CashReturn::CashReturn(double moneyCondition, double moneyReturn):moneyCondition_(moneyCondition), moneyReturn_(moneyReturn){}

double CashReturn::acceptCash(double money)
{
    double result = money;
    if (money > moneyCondition_)
    {
        result = money - floor(money/moneyCondition_)*moneyReturn_;
    }

    return result;
}

class CashContext
{
public:
    CashContext() = default;
    CashContext(CashType cashtype);
    inline double GetResult(double money){
        return cashsuper_->acceptCash(money);
    }

    ~CashContext(){
        if (cashsuper_ != nullptr){
            delete cashsuper_;
            cashsuper_ = nullptr;
        }
    }

private:
    CashSuper* cashsuper_;
};

CashContext::CashContext(CashType cashtype)
{
    switch (cashtype)
    {
        case cashnormal:
            cashsuper_ =  new CashNormal();
            break;
        case cashrebate:
            cashsuper_ =  new CashRebate(0.8);
            break;
        case cashreturn:
            cashsuper_ =  new CashReturn(300, 100);
            break;
        default:
            cashsuper_ =  nullptr;
    }
}

int main()
{
    CashContext* cashcontext = new CashContext(cashreturn);

    double totalprice = .0f;
    double unitprice = .0f;
    int num = 0;

    std::cout << "请输入商品单价: " << std::endl;
    std::cin >> unitprice;

    std::cout << "请输入商品数量: " << std::endl;
    std::cin >> num;

    totalprice = unitprice * num;

    totalprice = cashcontext->GetResult(totalprice);

    std::cout << "最终应付价格: " << totalprice << std::endl;

    delete cashcontext;

    return 0;
}