Dynamically allocating an array of pointers to objects - c++

Question

Question:
I have a class called croba.
In my console application I have a menu in which I can choose different options. After I choose an option, a switch statement checks my input and executes the block I chose.
In one of the cases I want the program to dynamicly alocate an array of pointers to class objects of a unknown size (the user is asked to input the size of the array), the catch is that the user input and the array must be alocated in the "case" block, but the alocated array has to be accessed globally later in the code. I declared a pointer to object globally like this:
croba *arrayOfObjectsPtr = NULL;
And here is the "case" block:
case 3:{
int numberOfElements;
int indexNumber;
if(!arrayOfObjectsPtr){
do{
cout << endl << "How many linked lists? "; cin >> numberOfElements;
}while(numberOfElements < 1);
croba *arrayOfObjectsPtrLocal[numberOfElements];
for (int i = 0; i < numberOfElements; i++){
arrayOfObjectsPtrLocal[i] = new croba;
}
}else{
cout << endl << "The array is already alocated!" << endl;
}
arrayOfObjectsPtr = arrayOfObjectsPtrLocal;
break;
}
I'm trying to figure out if there is a way to declare a pointer to an array of pointers to class objects globally and then alocating it later (because the number of elements is not known before).

Answer 1

In C++, the best practice is to use std::vector, which is the dynamic array class of the standard library. It is much nicer to use than C-style arrays. In your case it would look like this: std::vector<croba *> arrayOfObjectsPtr. Be careful though, because you will have to manually delete the pointers in the vector before destruction, like so:
for (auto& obj : arrayOfObjectsPtr)
delete obj;
If you don't want to perform the cleanup manually, like above, use a vector of smart pointers, like std::unique_ptr.
If you still want to use the old C-style array (which is not recommended), then declare it this way:croba** arrayOfObjectsPtr = new croba*[numberOfElements]. As for the cleanup, you'll have to do this:
for (int i = 0; i < numberOfElements; ++i)
delete arrayOfObjectsPtr[i];
delete[] arrayOfObjectsPtr;