我仍然围绕着课程，我仍然是C ++的新手。我的任务是：
创建三个与继承无关的小类 - 类 建筑，汽车和自行车。给每个班级一些独特的 与其他人没有共同的属性和行为 类。
编写一个只有纯虚拟的抽象类CarbonFootprint getCarbonFootprint方法。
让每个类继承自该抽象类和 实现getCarbonFootprint方法来计算合适的 该课程的碳足迹（查看一些解释的网站 如何计算碳足迹）。
编写一个创建三者中每个对象的应用程序 类，在向量中放置指向这些对象的指针 CarbonFootprint指针，然后遍历向量， 多态调用每个对象的getCarbonFootprint方法。
对于每个对象，打印一些识别信息和对象 碳足迹。
我无法弄清楚如何遍历vector <CarbonFootPrint>。我也不知道正在创建的对象是否实际被放入此向量中。到目前为止我的代码是：
#include <iostream>
#include <vector>
using namespace std;
class CarbonFootPrint
{
//class declarations
public:
virtual double getCarbonFootPrint();
};
//class implementation
double CarbonFootPrint::getCarbonFootPrint()
{
return 0;
}
class Building : CarbonFootPrint
{
//class declarations
public:
Building(double e = 0, int m = 12); //constructor
~Building(); //destructor
double setElectric();
virtual double getCarbonFootPrint();
private:
double electric;
int months;
};
//class implementation
Building::Building(double e, int m)
{
electric = e;
months = m;
}
Building::~Building()
{
}
double Building::setElectric()
{
cout << "Enter your monthly electric in KWH: " << endl;
cin >> electric;
return electric;
}
double Building::getCarbonFootPrint()
{
//I would like to print out the variable information for each object created
//and then
cout << "The carbon footprint for this house is " << endl;
//when it iterates through the vector.
return(electric * months);
}
class Car : CarbonFootPrint
{
public:
Car(double = 0, double = 0); //constructor
~Car(); //destructor
double setYearlyMiles();
double setAverageMPG();
virtual double getCarbonFootPrint();
private:
double yearlyMiles, averageMPG;
int co2 = 9;
};
//class implementation
Car::Car(double ym, double mpg)
{
yearlyMiles = ym;
averageMPG = mpg;
}
Car::~Car()
{
}
double Car::setYearlyMiles()
{
cout << "Enter in your yearly miles: " << endl;
cin >> yearlyMiles;
return yearlyMiles;
}
double Car::setAverageMPG()
{
cout << "Enter in your average miles per gallon: " << endl;
cin >> averageMPG;
return averageMPG;
}
double Car::getCarbonFootPrint()
{
//I would like to print out the variable information for each object created
//and then
cout << "The carbon footprint for this car is " << endl;
//when it iterates through the vector.
return((yearlyMiles * averageMPG) * co2);
}
class Bicycle : CarbonFootPrint
{
public:
Bicycle(double = 0, int = 34); //constructor
~Bicycle(); //destructor
double setMiles();
virtual double getCarbonFootPrint();
private:
int calories;
double miles;
};
//class implementation
Bicycle::Bicycle(double m, int c)
{
miles = m;
calories = c;
}
Bicycle::~Bicycle()
{
}
double Bicycle::setMiles()
{
cout << "Enter in number of miles: " << endl;
cin >> miles;
return miles;
}
double Bicycle::getCarbonFootPrint()
{
//I would like to print out the variable information for each object created
//and then
cout << "The carbon footprint for this bicycle is " << endl;
//when it iterates through the vector.
return (miles * calories);
}
这是我的主要计划：
int main()
{
vector <CarbonFootPrint> *list;
int answer, i;
cout << "Welcome to the Carbon Footprint Calculator!\n" << endl;
do
{
cout << "Main Menu\n" << endl;
cout << "1: Set house info.\n" << endl;
cout << "2: Set car info.\n" << endl;
cout << "3: Set bicycle info.\n" << endl;
cout << "4: Get carbon footprint for all items set.\n" << endl;
cin >> answer;
switch (answer)
{
case 1:
{
cout << "\n" << endl;
Building *anotherBuilding;
anotherBuilding = new Building;
anotherBuilding->setElectric();
cout << "\n" << endl;
break;
}
case 2:
{
cout << "\n" << endl;
Car *anotherCar;
anotherCar = new Car;
anotherCar->setYearlyMiles();
anotherCar->setAverageMPG();
cout << "\n" << endl;
break;
}
case 3:
{
cout << "\n" << endl;
Bicycle *anotherbike;
anotherbike = new Bicycle;
anotherbike->setMiles();
cout << "\n" << endl;
break;
}
case 4:
{
//have it iterate through the vector and print out each carbon footprint.
break;
}
default:
{
cout << answer << " is not a valid option" << endl;
break;
}
}
}
while (answer != 4);
system("pause");
return 0;
}
非常感谢任何帮助或指导！谢谢你的时间！
答案 0 :(得分：0)
你错过了一件至关重要的事情：
编写一个创建三个类中每个类的对象的应用程序，在CarbonFootprint指针的向量中放置指向这些对象的指针，然后迭代遍历向量，以多态方式调用每个对象的getCarbonFootprint方法。
而不是
vector <CarbonFootPrint> *list; // Pointer to a vector of CarbonFootPrint objects.
您需要使用
vector <CarbonFootPrint*> list; // A vector of CarbonFootPrint pointers.
而不是
{
cout << "\n" << endl;
Building *anotherBuilding;
anotherBuilding = new Building;
anotherBuilding->setElectric();
cout << "\n" << endl;
break;
}
使用
{
cout << "\n" << endl;
Building *anotherBuilding;
anotherBuilding = new Building;
anotherBuilding->setElectric();
// Add the pointer to the list of pointers.
list.push_back(anotherBuilding);
cout << "\n" << endl;
break;
}
对其他对象类型进行类似的更改。
最后，在对象上调用getCarbonFooPrint()：
for (auto item : list )
{
item->getCarbonFooPrint();
}
并删除对象：
for (auto item : list )
{
delete item;
}
答案 1 :(得分：0)
Re：您对R Sahu的帖子的评论（我太新了，不允许对其他帖子发表评论）
您无法访问基类，因为它默认为private，
class Building : CarbonFootPrint
class Car : CarbonFootPrint
class Bicycle : CarbonFootPrint
都是私下继承自CarbonFootPrint，这代表了“有一个”的关系，在这种情况下，虽然从语义上来说汽车有一个碳足迹，你实际上试图制作一个“is-a”关系，因为这些都是实现基类的对象，CarbonFootPrint的更好名称可能是CarbonFootPrintProducer。
这里的修复只是让它们全部公开继承
class Name : public Base
答案 2 :(得分：-1)
使用纯虚拟getCarbonFootprint方法编写一个抽象类CarbonFootprint。
你的类不是抽象的，因为函数不是纯虚函数，为此只需添加= 0
virtual double getCarbonFootPrint() = 0;
纯虚函数是不计算实现的函数，任何包含纯虚函数的类都称为“抽象”，无法实例化。在这种情况下，它可以帮助您识别CarbonFootPrint而不是CarbonFootPrint*向量，因为实例化将由编译器选取，尽管知道模板编译器错误，您已经有了一对这个简单错误的一百行错误消息。
完全公开：实际上可以定义纯虚函数，例如;
virtual double getCarbonFootPrint() = 0;
double CarbonFootPrint::getCarbonFootPrint()
{
// some code
return 0;
}
double Building::getCarbonFootPrint()
{
return CarbonFootPrint::getCarbonFootPrint();
}
这是合法的C ++，允许您定义默认实现，而CarbonFootprint仍然是一个抽象类。