How to declare a default constructor for subclass? - c++

Question

Very recently, I have started learning C++ full-time.
It is my understanding that constructors in C++ are not inherited by subclasses, and therefore must be declared in the subclass.
Below, I have a program that has a base class Car with a default constructor using default values for the 3 variables, then I have a subclass SportsCar that supposedly invokes the default constructor from the base class.
My problem is that I am having trouble figuring out a way to initialize the new variable acceleration for the subclass constructor to a value such as -2.
Here is my .h file
#include <iostream>
#include <string>
using namespace std;
#ifndef CAR_H_
#define CAR_H_
class Car {
public:
Car();
void SetName(string carName);
void SetMPH(int carMPH);
void SetPrice(double carPrice);
string GetName() const;
int GetMPH() const;
double GetPrice() const;
virtual void display() {
cout << "Car Information: " << endl;
cout << "Model Name: " << name << endl;
cout << "Top Speed: " << mph << " miles per hour" << endl;
cout << "Sales Price: $" << price << endl;
}
void SetInfo(string theName, int theMPH, double thePrice) {
name = theName;
mph = theMPH;
price = thePrice;
}
virtual ~Car() {
cout << "deletion complete" << endl;
}
private:
string name;
int mph;
double price;
};
Car::Car() {
name = "NoName";
mph = -1;
price = 0.0;
}
void Car::SetName(string carName) {
name = carName;
}
void Car::SetMPH(int carMPH) {
mph = carMPH;
}
void Car::SetPrice(double carPrice) {
price = carPrice;
}
string Car::GetName() const {
return name;
}
int Car::GetMPH() const {
return mph;
}
double Car::GetPrice() const {
return price;
}
class SportsCar : public Car {
public:
void SetAcceleration(double carAcceleration) {
acceleration = carAcceleration;
}
double GetAcceleration() const {
return acceleration;
}
void display() override {
Car::display();
cout << "0-60mph Acceleration: " << acceleration << endl;
}
private:
double acceleration;
};
#endif /* CAR_H_ */
Here is my .cpp file:
#include <iostream>
#include <string>
#include <vector>
using namespace std;
#include "Car.h"
int main() {
Car* nullCar;
Car* regularCar1;
Car* regularCar2;
SportsCar* nullSportsCar;
vector<Car*> carsList;
unsigned int i;
nullCar = new Car();
carsList.push_back(nullCar);
regularCar1 = new Car();
regularCar1->SetName("2022 Honda Civic");
regularCar1->SetMPH(140);
regularCar1->SetPrice(22550.79);
carsList.push_back(regularCar1);
regularCar2 = new Car();
regularCar2->SetInfo("2022 Nissan Altima", 130, 24900.49);
carsList.push_back(regularCar2);
nullSportsCar = new SportsCar();
carsList.push_back(nullSportsCar);
for (i = 0; i < carsList.size(); i++) {
carsList.at(i)->display();
cout << endl;
}
return 0;
}
Here is the output:
Car Information:
Model Name: NoName
Top Speed: -1 miles per hour
Sales Price: $0
Car Information:
Model Name: 2022 Honda Civic
Top Speed: 140 miles per hour
Sales Price: $22550.8
Car Information:
Model Name: 2022 Nissan Altima
Top Speed: 130 miles per hour
Sales Price: $24900.5
Car Information:
Model Name: NoName
Top Speed: -1 miles per hour
Sales Price: $0
0-60mph Acceleration: 0
It works fine, but I want the last output "0-60mph Acceleration" to read -2 instead of 0. I just don't know how to declare a default constructor for the subclass to do that.

Answer 1

Do you mean:
class SportsCar : public Car {
public:
SportsCar()
: Car() // Parent Init
// Preferrer using initializer list for members
// After Parents come members
, acceleration(-2)
{}
....
};