Reiterating through class vectors C++ - c++

Question

I am still wrapping my head around classes and am still new to C++. My assignment is:
Create three small classes unrelated by inheritance - classes
Building, Car and Bicycle. Give each class some unique appropriate
attributes and behaviors that it does not have in common with other
classes.
Write an abstract class CarbonFootprint with only a pure virtual
getCarbonFootprint method.
Have each of your classes inherit from that abstract class and
implement the getCarbonFootprint method to calculate an appropriate
carbon footprint for that class (check out a few websites that explain
how to calculate carbon footprints).
Write an application that creates objects of each of the three
classes, places pointers to those objects in a vector of
CarbonFootprint pointers, then iterates through the vector,
polymorphically invoking each object's getCarbonFootprint method.
For each object, print some identifying information and the object's
carbon footprint.
I am having trouble trying to figure out how to iterate through my vector <CarbonFootPrint>. I also do not know if the objects being created are actually being put into this vector. My code so far is:
#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);
}
Here is my main program:
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;
}
Any help or guidance is greatly appreciated! Thank you for your time!

Answer 1

Re: your comments on R Sahu's post (I'm too new to be allowed to comment on other posts)
You cannot access the base class because it has defaulted to private,
class Building : CarbonFootPrint
class Car : CarbonFootPrint
class Bicycle : CarbonFootPrint
are all inheriting from CarbonFootPrint privately, which represents a "has-a" relationship, in this case although semantically a car has-a carbon foot print you're actually trying to make an "is-a" relationship, as these are all objects that implement the base class, possibly a better name for CarbonFootPrint could be CarbonFootPrintProducer.
The fix here is simply make them all publically inherited
class Name : public Base

Answer 2

You missed a crucial thing from:
Write an application that creates objects of each of the three classes, places pointers to those objects in a vector of CarbonFootprint pointers, then iterates through the vector, polymorphically invoking each object's getCarbonFootprint method.
Instead of
vector <CarbonFootPrint> *list; // Pointer to a vector of CarbonFootPrint objects.
You need to use
vector <CarbonFootPrint*> list; // A vector of CarbonFootPrint pointers.
Instead of
{
cout << "\n" << endl;
Building *anotherBuilding;
anotherBuilding = new Building;
anotherBuilding->setElectric();
cout << "\n" << endl;
break;
}
Use
{
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;
}
Make similar changes to the other object types.
At the end, call CarbonFootPrint() on the objects:
for (auto item : list )
{
item->CarbonFootPrint();
}
and delete the objects:
for (auto item : list )
{
delete item;
}

Answer 3

R Sahu covered almost all of it, the only bit I see remaining is;
Write an abstract class CarbonFootprint with only a pure virtual getCarbonFootprint method.
to which your class is not abstract as the function is not pure virtual, to do this simply add = 0
virtual double getCarbonFootPrint() = 0;
Pure virtual functions are ones that don't count as implemented, any class containing a pure virtual function is called "abstract" and cannot be instantiated. In this case it would have helped you identify your vector of CarbonFootPrint rather than CarbonFootPrint* to them, as the instantiations would be picked up by the compiler, although knowing template compiler errors you'd have had a couple hundred lines of error message for this simple mistake.
For full disclosure: a pure virtual function can actually be defined, e.g.;
virtual double getCarbonFootPrint() = 0;
double CarbonFootPrint::getCarbonFootPrint()
{
// some code
return 0;
}
which can then be called from any derived class
double Building::getCarbonFootPrint()
{
return CarbonFootPrint::getCarbonFootPrint();
}
This is legal C++, allows you to define a default implementation, and still CarbonFootprint is an abstract class.