Initializing a private array of pointers to null

Question

I'm working on a C++ project which basically uses a couple of classes to simulate a retail environment; so far everything has gone smoothly, but I haven't been using C++ for very long and I'm a little stumped on how this array is supposed to work.

//Customer.h
private:
    std::array< CustomerOrder *, 3 > orderList;

Basically, the array is declared in the Customer.h file as private, but the Customer.h and Customer.cpp files also provide a method

addOrder(CustomerOrder *c)

for adding CustomerOrder pointers(CustomerOrder being another class) to the array. From my experience, the logic for the method is pretty straightforward: Use a for loop to find the first index containing a null pointer, then insert a pointer into that index.

The issue is, that involves first initializing the array to null pointers, and I'm not sure how or in which file I should do this. Since the array is private, I would assume I have to initialize it in the .h file using something along the lines of

for(size_t i = 0; i < orderList.size(); ++i)
    orderlist[i] = nullptr;

or

orderlist[3] = {nullptr}

Can I/Do I have to do this in a .h file? And is there a more trustable way to initialize the array?

For reference, I'm using the C++11 standard, if that makes any difference.

Answer 1

If this data member is private then it can be initialized either in a constructor or in some member function that will initialize it.

To set all elements of the array to nullptr you can use member function fill of class std::array.

For example

orderlist.fill( nullptr );

Answer 2

Use a constructor, and executable code isn´t supposed to be in a h-file.
And: Don´t do orderlist[3] = {nullptr} on a 3-sized array.
It only has the indizes 0,1,2. The loop is far better.