How can I reset a generic array?

given the following code:

template<class T>
class A{
    T* arr;
    int size;
public:
    A(T* arr, int size);

};

template<class T>
A<T>::A(int size) :
        arr(new T[size]), size(size) {
    for (int i = 0; i < size; i++) {
        arr[i] = T();
    }
}

It's ok to initialize the array like that? What in fact happens while I doing arr(new T[size]) , namely, which values will be in the array after this line?

If for example I want to create object from this class (with T=int) , exists a way to implement the constructor so that I will get in any cell 0 ?