Vector Array implementation in C++

vec.hpp

#ifndef VEC_HPP_INCLUDED
/*
 Author: Tymon Woźniak <https://github.com/Moderrek>
 Vector Array implementation in C++ by Tymon Woźniak
*/
#define VEC_HPP_INCLUDED

#include <iostream>
#include <string>

template <typename T>
class Vec {
public:
    Vec();
    Vec(const Vec& t);
    Vec(std::initializer_list<T> args);
    ~Vec();
    
    void operator=(const Vec& t);
    
    size_t size() const;
    T& operator[](size_t idx);
    const T& operator[](size_t idx) const;
    
    void push(T x);
    T pop();
private:
    void clone(const Vec& t);
    void free();
    
    T* tab;
    size_t length;
    size_t capacity;
};

template <typename T>
Vec<T>::Vec() {
    capacity = 1;
    tab = new T[capacity];
    length = 0;
}

template <typename T>
Vec<T>::Vec(const Vec& t) {
    clone(t);
}

template <typename T>
Vec<T>::Vec(std::initializer_list<T> args) {
    capacity = args.size();
    tab = new T[capacity];
    length = 0;
    for (auto i : args) {
        push(i);
    }
}

template <typename T>
void Vec<T>::operator=(const Vec& t) {
    if (this == &t) {
        return;
    }
    free();
    clone(t);
}

template <typename T>
Vec<T>::~Vec() {
    free();
}

template <typename T>
size_t Vec<T>::size() const {
    return length;
}

template <typename T>
T& Vec<T>::operator[](size_t idx) {
    return tab[idx];
}

template <typename T>
const T& Vec<T>::operator[](size_t idx) const {
    return tab[idx];
}

template <typename T>
void Vec<T>::clone(const Vec& t) {
    length = t.length;
    capacity = t.capacity;
    tab = new T[capacity];
    for (size_t i = 0; i < length; i += 1) {
        tab[i] = t.tab[i];
    }
}

template <typename T>
void Vec<T>::free() {
    delete[] tab;
}

template <typename T>
void Vec<T>::push(T x) {
    if (length == capacity) {
        capacity *= 2;
        T* tmp = new T[capacity];
        for (size_t i = 0; i < length; i += 1) {
            tmp[i] = tab[i];
        }
        delete[] tab;
        tab = tmp;
    }
    tab[length++] = x;
}

template <typename T>
T Vec<T>::pop(){
    return tab[--length];
}

template <typename T>
std::ostream& operator<<(std::ostream& os, const Vec<T>& tab) {
    os << '[';
    for (size_t i = 0; i < tab.size(); i += 1) {
        if (i > 0) os << ", ";
        os << tab[i];
    }
    os << ']';
    return os;
}

#endif

Example use

#include "vec.hpp"

int main() {
    Vec<int> vec = {1, 2, 3, 4};
    vec.push(5);
    std::cout << vec << '\n'; // [1, 2, 3, 4, 5]
    std::cout << vec.pop() << '\n'; // 5
    std::cout << vec << '\n'; // [1, 2, 3, 4]
    vec.push(4);
    std::cout << vec << '\n'; // [1, 2, 3, 4, 4]
    return 0;
}