在 C++ 中访问一个类的多个实例

Question

我正在为一家餐厅创建一个菜单，每个类别可以有 5 道菜。到目前为止，我已经为肉类菜肴创建了一个类，并且最多可以添加 5 道菜，每道菜都有一个唯一的标识符。我遇到的问题是在创建对象后访问它们。 （会有多个类别，因此为什么到目前为止只有一个 case 的 switch 语句）。

例如，我将如何实现更改第二道菜的描述的方法？

到目前为止，这是我的代码：

肉.h

    class Meat{
private:
    int meatNumber;
    std::string meatCategory;
    std::string meatDescription[MAX_ITEMS];
    double meatPrice[MAX_ITEMS];

    public:
        Meat();
        //setter functions
        int setMeatNumber();
        std::string setMeatDescription();
        double setMeatPrice();

        //getter functions
        int getMeatNumber();
        std::string getMeatCategory();
        std::string getMeatDescription(int i);
        double getMeatPrice(int i);
    };

肉.cpp

#include "Meat.h"

//constructor
    Meat::Meat() {
    meatNumber = 0;
    meatCategory = "Meat";
    meatDescription[MAX_ITEMS] = "No description written.";
    meatPrice[MAX_ITEMS] = 0.0;
}

//setter functions
int Meat::setMeatNumber(){
    static int counter = 1;
    meatNumber = counter++;
}

    std::string Meat::setMeatDescription(){
        int i = 0;
        std::cout << "Please enter a short description: " << std::endl;
        std::cin >> meatDescription[i];
        return meatDescription[i];
    }

    double Meat::setMeatPrice(){
        int i = 0;
        std::cout << "Please set the price in a 00.00 format: " << std::endl;
        std::cout << "£";
        while(!(std::cin >> meatPrice[i])){
           std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n');
           std::cout << "Error. Please enter a number: ";
        }
        return meatPrice[i];
    }

    //getter functions
    int Meat::getMeatNumber() { return meatNumber; }
    std::string Meat::getMeatCategory() { return meatCategory; }
    std::string Meat::getMeatDescription(int i) {return meatDescription[i]; }
    double Meat::getMeatPrice(int i) { return meatPrice[i]; }

main.cpp

    #include <iostream>
#include "Meat.h"



int main() {
int choice;

    std::cout << "Menu Creation Terminal\n\n" << std::endl;
    std::cout << "\t Welcome\nto Wrapid™ Restaurants\n\n" << std::endl;
    std::cout << "1. Add Meat Dish\n2. Add Fish Dish\n3. Add Vegetarian Dish\n4. Add Drink\n"
                 "5. Edit Current Menu\n6. Quit\n\n" << std::endl;
    std::cout << "Please select an option: ";
    std::cin >> choice;

    switch (choice) {
        case 1:
            {
            int option = true;
            int count = 0, i;
            Meat meatDish;
            std::cout << "Meat Dishes" << std::endl;
            while (true) {
                meatDish.setMeatNumber();
                meatDish.setMeatDescription();
                meatDish.setMeatPrice();

                //functions to add details to dish
                std::cout << "You have added the following dish: " << std::endl;
                std::cout << "Item number: \n" << meatDish.getMeatNumber() << std::endl;
                std::cout << "Item Category: \n " << meatDish.getMeatCategory() << std::endl;
                std::cout << "Item Description: \n" << meatDish.getMeatDescription(i) << std::endl;
                std::cout << "Item Price: \n £" << meatDish.getMeatPrice(i) << std::endl;

                std::cout << "Would you like to add another item? Press 1 for yes or 2 for no: " << std::endl;
                std::cin >> option;
                count += 1;
                if (count == 5) {
                    std::cout << "Error. Exceeded maximum items.";
                    break;
                } //breaks out of loop if more than 5 items
                if (option == 2) { break; } //breaks out of loop when user is finished adding items
            }//while loop to contain menu
        }//brace for scope of case 1
}


return 0;

}

Answer 1

当您使用 c++ 类 Meat 时，您可以使用 [] 来实例化 N 个项目

例如5 对象

 Meat meats[5];

如果你想修改第二个对象，那么

 meats[1].setMeatDescription(<pass argument>);

您需要使用 this 关键字更改该方法

 this->meatDescription = <pass argument>; 

无需将meatDescription[] 创建为数组

使用这个代码https://pastebin.com/bCkzbFZV你可以使用meats[i].getMeatDescription()

Answer 2

您可以创建一个名为 DishesContainer 的新类。这个类可能有：

• 一个私有的 std::vector => 它将保存每个实例
• 创建新菜的公共函数
• 一个公共函数，用于更改菜肉中的任何类型的值。

例如更改描述

class DishContainer{
public:
    void ChangeDescription(int indexMeat, std::string newDescription){
        meats_[indexMeat].setMeatDescription(newDescription);
    }

private:
    std::vector<Meat> meats_;
}