Vector & Array

#include <iostream>

template<typename T>
class Vector {
private:
    T* data_;
    size_t size_;
    size_t capacity_;

public:
    Vector(): data_(nullptr), size_(0), capacity_(0) {}

    Vector(size_t n_): size_(n_), capacity_(n_) {
        data_ = new T[n_];
    }

    ~Vector() {
        delete [] data_;
    };

    T& operator[] (size_t index) {
        return data_[index];
    }
    
    const T& operator[] (size_t index) const {
        return data_[index];
    } 

    size_t size() const {
        return size_;
    }

    void push_back(const T& value) {
        if(size_ == capacity_) {
            capacity_ = size_ == 0? 1: 2 * capacity_;
            T* new_data_ = new T[capacity_];

            for(size_t i = 0; i < size_; i++) {
                new_data_[i] = data_[i];
            }
            delete[] data_;
            data_ = new_data_;
        }
        data_[size_] = value;
        size_++; 
    }

};

template<typename T, size_t size_>
class Array {
private:
    T data_[size_];

public:
   T& operator[] (size_t index) {
        return data_[index];
    }
    
    const T& operator[] (size_t index) const {
        return data_[index];
    } 

    size_t size() const {
        return size_;
    }
};

int main() {
    Vector<int> vec;
    vec.push_back(10);
    vec.push_back(2);
    for(int i =0; i < vec.size(); i++) 
        std::cout << vec[i] << '\n';

    Array<int, 3> arr{};
    arr[1] = 9;
    for(int i =0; i < arr.size(); i++) 
        std::cout << arr[i] << '\n';
        
    return 0;
}