Шаблонный класс

#include <iostream>
using namespace std;
 
template <class T>
class Vector{
private:
    int size, capacity;
    T* data;
public:
    Vector(){
        this->capacity = 5;
        this->size = 0;
        this->data = new T[this->capacity];
    };
    Vector(int size){
        if(size <=0 ) size = 1;
        this->size = size;
        this->capacity = 1;
        while(this->capacity < this->size) this->capacity = this->capacity*2;
        data = new T[this->capacity];
    };
    Vector(const T* data, int size){
        if(size==0){
            this->capacity = 5;
            this->size = size;
            this->data = new T[this->capacity];
        }
        else{
            this->size = size;
            this->capacity = size;
            this->data = new T[this->size];
            for(int i=0; i<this->size; i++)
                this->data[i] = data[i];
        }
    };
    virtual ~Vector(){
        delete[]data;
    };
    void push_back(T elem){
        T* newdata;
        if(size > capacity) {
            capacity = capacity * 2;
            newdata = new T[capacity];
            for (int i=0; i<size; i++)
                newdata[i] = data[i];
            delete[] data;
            data = newdata;       
        }
        data[size] = elem;
        size++;
    };
    T& operator[](int i){
        return this->data[i];
    };
    int getSize() const{
        return this->size;
    };
    friend ostream& operator<<(ostream& out, const T& diy){
        if(this->size == 0) out<< "Empty";
        else out<< diy;
    };
};
 
struct day_in_year{
    int month, day;
    day_in_year(int d=1, int m=1):day(d),month(m){}
};
 
std::ostream& operator<<(std::ostream& out, const day_in_year& diy){
    out << diy.day << "." << diy.month;
}
 
 
int main(){
    Vector<day_in_year> v;
    cout << v << "\n";
    return 0;
}

template <class T>
std::ostream& operator<<(std::ostream &stream, const std::vector<T> &vec)
{
    stream << "[";
    if (vec.size() != 0) {
        stream << vec[0];
        for (int i = 1; i < vec.size(); i++) {
            stream << ", " << vec[i];
        }
    }
    steam << "]";
    return stream;
}