How do I deallocate the dynamic memory correctly in this simple C++ program? I get a segmentation fault (core dump) when I execute the program. I am trying to find out where I went wrong. Thanks in advance.
I am trying to add dynamically allocated objects to an array and am trying to get the destructor to clear the memory. I am unsure if I have created the destructor correctly in carList.
#include <iostream>
#define MAX 3
class Car{
public:
Car(std::string name){
this->name = name;
}
~Car(){
}
std::string getName(){
return this->name;
}
private:
std::string name;
};
class carList{
public:
carList(){
this->length = 0;
}
~carList(){
//the deconstructer; I am unsure If I have implemented it correctly
for (int i = 0; i < this->length; i++)
{
if(listCar[i] != nullptr){
delete[] listCar[i];
}
}
}
int getLength(){
return this->length;
}
// adding to the end of the list, unsure whether Implemented correctly
void addEndList(Car* car){ //???
if(this->length < MAX){
this->listCar[length+1] = car;
this->length++;
}
}
private:
Car* listCar[MAX];
int length;
};
int main(){
carList* carlist = new carList();
std::cout << carlist->getLength() <<std::endl;
Car* car2 = new Car("one");
Car* car3 = new Car("two");
carlist->addEndList(car2);
carlist->addEndList(car3);
std::cout << carlist->getLength() <<std::endl;
std::string name1 = car2->getName();
std::cout << name1 << std::endl;
delete carlist; // deleting the carlist, unsure if I need to delete car2,
//and car3 or if the destructor handles that, which I am
//trying to implement
return 0;
}
>Solution :
Array indexes starts at 0 in C++. So,
this->listCar[length+1] = car;
should be
this->listCar[length] = car;
Otherwise you don’t initialize index 0, but you delete it.
Second problem is with the delete. You should use delete for pointer returned by new and delete[] for new[]. You used new. So,
delete[] listCar[i];
should be
delete listCar[i];
After these 2 changes it looks okay: https://godbolt.org/z/84M1fq1fv