Question

I have this annoying error in my program.

“Vehicle” is the Base class.
“Bicycle” extends this class.

#ifndef BICYCLE_H
#define BICYCLE_H

#include "Vehicle.h"

#include <string>
#include <iostream>
using namespace std;

//Template class which is derived from Vehicle
template<typename T>
class Bicycle: public Vehicle
{
public:
    Bicycle();
    Bicycle(int, int, string, int); 
    ~Bicycle();

    //Redefined functions inherited from Vehicle
    void move(int, int); // move to the requested x, y location divided by 2
    void set_capacity(int); // set the capacity value; can't be larger than 2

};

Above is the Bicycle.h file (I do not have .cpp file for this class)

#ifndef VEHICLE_H
#define VEHICLE_H

#include "PassengerException.h"

#include <string>
#include <iostream>
using namespace std;


//ADD LINE HERE TO MAKE IT A TEMPLATE CLASS
template<typename T>
class Vehicle
{
public:
    Vehicle(); //default contstructor
    Vehicle(int, int, string, int); // set the x, y, name, and capacity
    virtual ~Vehicle(); //destructor; should this be virtual or not???


    //Inheritance - question #1; create these functions here and in Bicycle     class
    string get_name(); // get the name of the vehicle
    void set_name(string); //set the name of the vehicle
    void print(); // std print function (GIVEN TO YOU)

    //Polymorphism - question #2
    virtual void move(int, int); // move to the requested x, y location
    virtual void set_capacity(int); // set the capacity value

    //Operator overloading - question #3
    Vehicle<T> operator+(Vehicle<T> &secondVehicle) const;

    //Exceptions - question #4
    T get_passenger(int) throw(PassengerException); // get the passenger at the specified index
    void add_passenger(T) throw(PassengerException); // add passenger and the current passenger index
    void remove_passenger() throw(PassengerException); // remove a passenger using current passenger index


protected:
    int x_pos;
    int y_pos;
    string name;
    int capacity;
    T *passengers;
    int current_passenger;
};

Above is the Vehicle.h file. I do not have .cpp for this either.

Also, what do the ifndef define endif mean? Do I have to use those? Are they required?

And, do their names have to be formatted like that?

Answer 1

class Bicycle: public Vehicle

Vehicle is a template, so you need this:

class Bicycle: public Vehicle<T>

The #ifndef and #define and #endif are called header guards and are used to prevent your header file from being included more than once, causing things (classes) to be declared more than once.