Container 2020 day 1

#pragma once
#include <algorithm>
#include <numeric>
namespace API
{
    class Container
    {
    public:
        using iterator = int*; //aliases for generic code
        friend void swap(Container& a, Container& b) noexcept;

        Container() = default;
        explicit Container(size_t count) : _count(count), _data(new int[count]){
            std::iota(begin(), end(), 0);
        };

        explicit Container(const Container& that) { //copy ctor
            _data = new int[that._count];
            _count = that._count;
            std::copy(that.begin(), that.end(), _data);
        }

        Container(Container&& that) noexcept {
            _count = that._count;
            _data = that._data;
            that._data = nullptr;
            that._count = 0;
        }

        Container& operator=(Container&& that) noexcept {
            std::swap(_data, that._data);
            std::swap(_count, that._count);
            return *this;
        }

        void swap(Container& that) noexcept {
            using std::swap;
            swap(_data, that._data);
            swap(_count, that._count);
        }

        Container& operator=(const Container& that) { // copy assignment
            delete[] _data;
            _data = new int[that._count]; //overwrites an existing pointer
            _count = that._count;
            std::copy(that.begin(), that.end(), _data);
            return *this;
        }

        ~Container() {
            delete[] _data;
        }

        iterator begin() const noexcept { return _data; }
        iterator end() const noexcept { return _data + _count; }


    private:
        int* _data = nullptr;
        size_t _count = 0;
    };

    void swap(Container& a, Container& b) noexcept {
        a.swap(b);
    }
}