Question

Let’s say I have a class that has a member which is an array. Is it possible to define its size upon construction/at run-time, in the following way:

class myClass {
    private:
        int myArray[n]
    public:
        myClass();
        someOtherMethod();
};

Where n is a variable that is defined based on user input. If not, what would be the best alternative?

Answer 1

Use a vector.

class myClass {
    private:
        std::vector<int> myArray;
    public:
        myClass();
        someOtherMethod();
};

myClass::myClass (int size)
    : myArray (size)
{ 
    ...
}

Then, you can fill in the vector as you would an array. Alternatively, as Nawaz points out, use reserve(), which reserves space for new elements, and/or push_back(), which adds elements onto the back, one at a time.