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;
}
}
}
答案 0 :(得分:2)
vector<Attraction>
执行对象切片,因此您永远无法访问派生类的getPrice()
。您需要使用多态,而在double GetPrice()
类中使用虚拟Attraction
方法,然后将vector<Attraction*>
与new
/ delete
一起用于对象。不要忘记在Attraction
虚拟中使析构函数,所以你可以使用基指针delete
后代对象。
答案 1 :(得分:2)
您所尝试执行的操作无法使用您显示的代码。您没有正确使用多态性。
尝试更像这样的东西:
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;
//...
}
}