如何查看每个子类的价格

How can I check price of each sub class?

本文关键字：子类 何查看      更新时间：2023-10-16
class Attraction {
};
class Museum : public Attraction {
private:
    double price;
public:
    void setPrice(double Price) {
        price = Price;
    }
    double getPrice() {
        return price;
    }
};
class Park : public Attraction {
public:
    double getPrice() {
        return 0;
    }
};
class Theatre : public Attraction {
private:
    double price;
public:
    void setPrice(double Price) {
        price = Price;
    }
    double getPrice() {
        return price;
    }
};
int _tmain(int argc, _TCHAR* argv[]) {
    vector<Attraction> attraction;
    vector<Attraction>::iterator i;
    for (i = attraction.begin(); i != attraction.end(); i++) {
        if (i->getPrice() < 5) {
            cout << endl;
        }
    }
}

vector<Attraction>执行对象切片，因此您永远无法访问派生类getPrice()。您需要改用多态性，其中您在Attraction类中有一个虚拟double GetPrice()方法，然后对对象使用 vector<Attraction*> new/delete。 不要忘记将析构函数也设置为虚拟Attraction这样您就可以使用基指针delete后代对象。

您尝试执行的操作无法使用您显示的代码执行。 您没有正确利用多态性。

尝试更多类似的东西：

class Attraction
{
public:
    Attraction() {}
    virtual ~Attraction() {}
    virtual double getPrice(double Price)
    {
        return 0.0;
    }
};
class PriceyAttraction : public Attraction
{
private:
    double price;
public
    PriceyAttraction(double Price = 0.0) : Attraction(), price(Price) {}
    virtual double getPrice()
    {
        return price;
    }
    void setPrice(double Price)
    {
        price = Price;
    }
};
class Museum : public PriceyAttraction
{
public:
    Museum(double Price = 0.0) : PriceyAttraction(Price) {}
};
class Park : public Attraction
{
public:
    Park() : Attraction() {}
};
class Theatre : public PriceyAttraction
{
public:
    Theatre(double Price = 0.0) : PriceyAttraction(Price) {}
};
int _tmain(int argc, _TCHAR* argv[])
{
    std::vector<Attraction*> attraction;
    attraction.push_back(new Museum(5.00));
    attraction.push_back(new Park);
    attraction.push_back(new Theatre(7.50));
    std::vector<Attraction*>::iterator i;
    for (i = attraction.begin(); i != attraction.end(); ++i)
    {
        std::cout << i->getPrice() << std::endl;
        //...
    }
    for (i = attraction.begin(); i != attraction.end(); ++i)
    {
        delete *i;
    }
}

如果您使用的是 C++11 或更高版本，则可以使用 std::unique_ptr 为您管理对象解除分配：

int _tmain(int argc, _TCHAR* argv[])
{
    std::vector<std::unique_ptr<Attraction>> attraction;
    attraction.emplace_back(new Museum(5.00));
    attraction.emplace_back(new Park);
    attraction.emplace_back(new Theatre(7.50));
    /* or:
    attraction.push_back(std::unique_ptr<Attraction>(new Museum(5.00)));
    attraction.push_back(std::unique_ptr<Attraction>(new Park));
    attraction.push_back(std::unique_ptr<Attraction>(new Theatre(7.50)));
    */
    /* or:
    attraction.push_back(std::make_unique<Museum>(5.00));
    attraction.push_back(std::make_unique<Park>());
    attraction.push_back(std::make_unique<Theatre>(7.50));
    */
    vector<Attraction>::iterator i;
    for (i = attraction.begin(); i != attraction.end(); ++i)
    {
        std::cout << (*i)->getPrice() << std::endl;
        //...
    }
}
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