Question

For example i have class with constructor that has array of ints as parameter:

A(int* array) : m_array(array) {}

I can use it like this:

int array[] = { ... }
A a(array);

Or like this:

int* array = new int[10];
A a(array);

If object then use it array, it must (or may be not?) delete it in desctructor (if it was dynamic). But how he will know, that memory for this array was allocated dynamically?

Answer 1

You can’t know if it’s dynamically allocated or not, because after all, int* array is an int pointer, not an array. You might as well pass:

int i;
A a(&i);

As you can imagine, bad things will happen if you try to delete[] that one, or try to access m_array[N] with N > 0.

So you have to rely on the caller to do the right thing; there’s nothing you can do to verify or enforce it. All you have is the address of an int. Who created that int, or how or whether more ints follow after it, will be unknown.

If you want more safety, use an std::vector. This is what it was made for.