Segmentation Fault 11 in C++ when accessing second element in array - c++

Question

In short, I have a C++ program that consists of a Car class with subclasses SportsCar and SUV, as well as a CarInventory that stores the Car objects.

Answer 1

I think the problem is in the insert function
void CarInventory::insert(Car *car) {
for (int i = 0; i < inventorySize; i++) {
if (carArray[i]) {
i++;
}
When you find a car already in in your carArray you increment i, but then you increment i again in the for-loop. That way you will skip every other position in the array, and they will remain uninitialized.

Answer 2

You allocated an array of 10 cars. But you only initialized it with 4 cars.
So when your loop in displayVehichles gets around to accessing carArray[5] it will likely be accessing uninitialized memory.
This statement seems troublesome:
carArray = new Car *[maxStock];
It should probably be:
carArray = new Car *[maxStock];
for (int i = 0; i < maxStock; i++)
{
carArray[i] = NULL;
}
totalNumCars = 0;
That way, your insert method will behave correctly. But your insert method could be much simpler:
void CarInventory::insert(Car *car) {
if (totalNumCars < maxStock)
carArray[totalNumCars] = car;
totalNumCars++;
}
}
Further, while it's OK the way you have it the cars you have declared go out of scope BEFORE your CarInventory goes out of scope, it will be referencing Car objects that have already been deleted.
Use std::vector to hold your cars:
class CarInventory
{
std::vector<Car*> _cars;
public:
void displayVehicles()
{
for (auto i = _cars.begin(); i != _cars.end(); i++)
{
i->printInfo();
}
}
void insert(Car* car)
{
_cars.push_back(car);
}
};
Now that still doesn't solve the problem of your CarInventory class holding onto pointers of stack objects.
This is even better:
class CarInventory
{
std::vector<std::shared_ptr<Car>> _cars;
public:
void displayVehicles()
{
for (auto i = _cars.begin(); i != _cars.end(); i++)
{
i->printInfo();
}
}
void insert(std::shared_ptr<Car>& spCar)
{
_cars.push_back(spCar);
}
};
Then your code to use the class:
std::shared_ptr<Car*> createCar(const char* vin, const char* make, const char* color, int year)
{
Car* car = new Car(vin, make, color, year);
return std::shared_ptr<Car>(car);
}
int main(int argn, char *argv[])
{
CarInventory cars;
std::shared_ptr<Car*> toyota = createCar("2GCGC34M9F1152828", "Toyota", "Camry", "Green", 2012);
std::shared_ptr<Car*> honda = createCar("1C4BJWAG4DL602733", "Honda", "Civic", "Blue", 2015);
...
CarInventory cars;
cars.insert(toyota);
cars.insert(honda);
cout << "\n";
cars.displayVehicles();
}