Реализация enum class

#include <iostream>
#include "iPhone.h"
#include "Inventory.h"
 
 
using namespace std;
 
 
void fill(Inventory& i)
{
    //HERE we are adding iPhone instances to the inventory items
    i.add_item("iPhone 5s", 4.0, 16, "Silver");
    i.add_item("iPhone 6", 4.7, 64, "Space Gray");
    i.add_item("iPhone 6 Plus", 5.5, 64, "Silver");
    i.add_item("iPhone 6s", 4.7, 128, "Gold");
    i.add_item("iPhone 6s Plus", 5.5, 128, "Rose Gold");
}
 
//Here is the change added aditional "&"
void show(iPhone&& item)
{
    cout <<item.get_modelName() << ", "
         << item.get_screenSize()<< " inches, "
         << item.get_capacity() << " GB, "
         << item.get_colour() << ". "
         << endl;
}
int main()
{
    Inventory inventory;
    inventory.init();
    fill(inventory); // HERE the code calls function, which will add iPhone instances to the inventory items
    
    
    
    iPhone query1;
    query1.init("iPhone 6s Plus", 0, 0, "");
    cout << "Here are the results of search:" << endl;
    show(inventory.find_item(query1)); // HERE the code "inventory.find_item()"calls the function Inventory::find_item(…) to return nearest matching instance
    
    
    
    iPhone query2;
    query2.init("", 0, 0, "Gold");
    show(inventory.find_item(query2)); // HERE the code "inventory.find_item()"calls the function Inventory::find_item(…) to return nearest matching instance
    
    cout <<"\n";
#ifndef NDEBUG
    cout << "Press enter to exit" << endl;
    cin.get();
#endif
    
    return 0;
}

#ifndef iPhone_h
#define iPhone_h
 
 
 
#include <string>
 
class iPhone
{
public:
    void init(std::string modelName, float screenSize, int capacity, std::string colour);
    
public:
    std::string get_modelName() { return _modelName; }
    float get_screenSize() { return _screenSize; }
    int get_capacity() { return _capacity; }
    std::string get_colour() { return _colour; }
    
private:
    std::string _modelName;
    float _screenSize;
    int _capacity;
    std::string _colour;
    
};
#endif /* iPhone_h */

#include "iPhone.h"
#include <stdio.h>
 
void iPhone::init(std::string modelName, float screenSize, int capacity, std::string colour)
{
    _modelName = modelName;
    _screenSize = screenSize;
    _capacity = capacity;
    _colour = colour;
    
};

#ifndef Inventory_h
#define Inventory_h
#pragma once
#include "iPhone.h"
 
class Inventory
{
 
public:
    // Initializes inventory for storing abstraction objects
    void init() { _count = 0; }
    
    // Returns the number of currently stored abstraction objects
    size_t get_count() {  return _count; }
    
    // Returns stored abstraction object by its index or default if index is invalid
    iPhone get_item(size_t i) { return (i <_count) ? _items[i] : iPhone(); }
    
    // From passed property values, creates and adds new abstraction object in an array _items
    void add_item(std::string modelName, float screenSize, int capacity, std::string colour);
    
    // Looks for a matching abstraction object and returns the first found or default object
    iPhone find_item(iPhone& query);
    
private:
    // The maximum number of abstraction objects that can be stored
    static const size_t MAX_SIZE{ 10 };
    
    // An actual array for storing abstraction objects
    iPhone _items[Inventory::MAX_SIZE];
    
    // The number of currently stored abstraction objects in the array _items
    size_t _count;
 
};
 
 
#endif /* Inventory_h */

#include "Inventory.h"
 
void Inventory::add_item(std::string modelName, float screenSize, int capacity, std::string colour)
{
    if (_count < Inventory::MAX_SIZE)
    {
        iPhone new_item;
        new_item.init( modelName, screenSize,  capacity,  colour);
        _items[_count] = new_item;
        _count++;
    }
}
 
iPhone Inventory::find_item(iPhone &query)
{
    for (size_t i = 0U; i < _count; i++)
    {
        iPhone& item = _items[i];
        
        //for string type property
        if (query.get_modelName()!= ""
            && query.get_modelName() != item.get_modelName())
            continue;
        
        // for number type property
        if (query.get_screenSize() != 0
            && query.get_screenSize() != item.get_screenSize())
            continue;
        // for number type property
        if (query.get_capacity() != 0
            && query.get_capacity() != item.get_capacity())
            continue;
        //for string type property
        if (query.get_colour()!= ""
            && query.get_colour() != item.get_colour())
            continue;
        return item;
        
    }
    return iPhone{};    // return the default value object (or null object)
}