C++DynamicArray（vector）

    #include <iostream>
    
    using namespace std;
    
    #ifndef Dynamic_Num
    #define Dynamic_Num
    
    template <class T>
    class DynamicVector{
    public:
        template<class Y>
        friend ostream &operator<<(ostream &out, const DynamicVector<Y> &obj);
    
        DynamicVector() : array(NULL), mallocSize(0), numOfItems(0), virtualZero(0) {}
        DynamicVector(int index) : array(NULL), mallocSize(0), numOfItems(0), virtualZero(index) {}
        DynamicVector(T * const begin, T * const end,int index=0);
        DynamicVector(const DynamicVector &obj);