How to assign an object of another class to a field in a class constructor?

Question

C++ / C#

Hello everyone, how to assign an object of another class to a field in a class constructor, I do this:

class Stack
{
private:
    DynamicArray *arr;
public:
    Stack() {
        this->arr = new DynamicArray();
    }
}

There is no syntax error, the methods of the DynamicArray class in the IDE are autocompleted, called without an error, but do not work.
Thanks in advance

Answer 1

In general, the code is correct, what exactly does not work?
can it be like this

class Stack
{
private:
    DynamicArray *arr;
public:
    Stack()  : arr(new DynamicArray())
    {
        assert(arr);
    }
}