c++ - 修改 C++ vector 中的对象值时出现问题

Question

我正在尝试用 C++ 为游戏开发库存系统。我有 2 个头文件，一个名为 item，另一个 inventory，它们被发送到我的主要方法中。我设置代码的方式是，当我将 Item 对象发送到我的 list 时， list 会检查是否存在具有相同 ID 的对象。如果是，则获取数量 Item 值并将其递增 1。问题是对 Quantity 值的更改不会保存到主 Inventory 对象中。任何和所有帮助将不胜感激。如果我的代码不好，也很抱歉!我不会包含所有代码，但我确信所有正确的#include 函数都包含在内!

真正的问题似乎出在没有添加到主 Inventory 对象的实际新 Quantity 值中。

#include "stdafx.h"
#include <iostream>
#include "Windows.h"
#include "Item.h"
#include "Inventory.h"
#include <ctime>
#include <fstream>
#include <conio.h>
#include <stdio.h>
#include <windows.h>
#include <string>
#include <cstdio>
#include <vector>







// Functions!
void gotoxy(int x, int y)
{
    COORD coord;
    coord.X = x;
    coord.Y = y;
    SetConsoleCursorPosition(GetStdHandle(STD_OUTPUT_HANDLE), coord);
}

void setColor(int color) // 0 Black, 1 Blue, 2 Green, 3 Light Blue, 4Red 5     Purple 6 Yellow 7 White
{
    HANDLE  hConsole;
    hConsole = GetStdHandle(STD_OUTPUT_HANDLE);

    SetConsoleTextAttribute(hConsole, color);

}
void clearColor()
{
    HANDLE  hConsole;
    hConsole = GetStdHandle(STD_OUTPUT_HANDLE);

    SetConsoleTextAttribute(hConsole, 7);

}
void ShowConsoleCursor(bool showFlag)
{
    HANDLE out = GetStdHandle(STD_OUTPUT_HANDLE);

    CONSOLE_CURSOR_INFO     cursorInfo;

    GetConsoleCursorInfo(out, &cursorInfo);
    cursorInfo.bVisible = showFlag; // set the cursor visibility
    SetConsoleCursorInfo(out, &cursorInfo);
}






//
// Menu SetUp!

void menuArea()
{
    gotoxy(40, 4);
    setColor(2);
    std::cout << "--------Menu--------" << std::endl;

    gotoxy(40, 12);
    std::cout << "--------------------" << std::endl;
    clearColor();

}

void gatherArea()
{
    gotoxy(45, 6);
    setColor(3);
    std::cout << "-Gather" << std::endl;
    clearColor();
}
void recoveryArea()
{
    gotoxy(45, 8);
    setColor(5);
    std::cout << "-Recovery" << std::endl;
    clearColor();
}
void inventoryArea()
{
    gotoxy(45, 10);
    setColor(4);
    std::cout << "-Inventory" << std::endl;
    clearColor();
}
//
// Menu Selector!
void gatherOption()
{
    gotoxy(40, 6);
    std::cout << "(G)" << std::endl;
}
void recoverOption()
{
    gotoxy(40, 8);
    std::cout << "(R)" << std::endl;
}
void inventoryOption()
{
    gotoxy(40, 10);
    std::cout << "(I)" << std::endl;
}
void gatherSelected()
{
    setColor(5);
    gotoxy(40, 6);
    std::cout << "(G)" << std::endl;
    clearColor();
}
void recoverSelected()
{
    setColor(5);
    gotoxy(40, 8);
    std::cout << "(R)" << std::endl;
    clearColor();
}
void inventorySelected()
{
    setColor(5);
    gotoxy(40, 10);
    std::cout << "(I)" << std::endl;
    clearColor();
}
//
// Menu Viewer!

void viewClear()
{
    gotoxy(0, 4);
    for (int i = 0; i < 40; i++)
    {
        std::cout << "\t\t\t\t\t" << std::endl;
    }



}

void viewGather()
{
    gotoxy(12, 4);
    std::cout << "-----Gather-----\n" << std::endl;
    std::cout << "\t 1) Gather Wood    (5 sec)\n" << std::endl;
    std::cout << "\t 2) Gather Berries (5 sec)\n" << std::endl;

}
void viewRecover()
{
    gotoxy(12, 4);
    std::cout << "-----Recover-----\n" << std::endl;
    std::cout << "\t 1) Eat Berries (5 sec)\n" << std::endl;
    std::cout << "\t 2) Sleep      (10  sec)\n" << std::endl;


}




//
// Figuring out the inventory

void viewInventory(Inventory inventory)
{
    std::string inv = inventory.display(inventory);
    gotoxy(12, 4);
    std::cout << inv << std::endl;
}


Inventory setInventory(Inventory inventory)
{
    Item woodItem(1, "Wood;");
    Item berriesItem(2, "Berries");

    inventory.addItem(woodItem);
    inventory.addItem(berriesItem);

    return inventory;
}

//
//Timer Stuff!
void timerSetup()
{
    setColor(6);
    gotoxy(5, 2);
    std::cout << "Client Up Time:" << std::endl;
    clearColor();

}

void getUpTime()
{
    gotoxy(22, 2);
    int seconds = (int)std::clock() / 1000;
    int minutes = (int)seconds / 60;
    seconds = seconds % 60;
    if (seconds < 10 && minutes < 10)
        std::cout << "0" << minutes << ":0" << seconds << std::endl;

    else if (seconds < 10)
        std::cout << minutes << ":0" << seconds << std::endl;

    else if (minutes<10)
        std::cout << "0" << minutes << ":" << seconds << std::endl;
    else
        std::cout << minutes << ":" << seconds << std::endl;
}

//
void drawMenu()
{
    menuArea();
    gatherArea();
    recoveryArea();
    inventoryArea();
    timerSetup();
    gatherOption();
    recoverOption();
    inventoryOption();

}





int main()
{

    Inventory inventory;
    drawMenu();
    std::clock_t start;
    inventory = setInventory(inventory);



    while (true)
    {
        ShowConsoleCursor(false);
        getUpTime();


        if (GetAsyncKeyState(0x47)) //G
        {
            gatherSelected();
            recoverOption();
            inventoryOption();
            viewClear();
            viewGather();
        }
        if (GetAsyncKeyState(0x52))//R
        {
            recoverSelected();
            gatherOption();
            inventoryOption();
            viewClear();
            viewRecover();
        }
        if (GetAsyncKeyState(0x49))//I
        {
            Item admin(0, "Test");
            inventory.addItem(admin);
            inventorySelected();
            gatherOption();
            recoverOption();
            viewClear();
            Item bannana(3, "Bannana");
            inventory.addItem(bannana);
            viewInventory(inventory);



        }
        if (GetAsyncKeyState(VK_ESCAPE))//Esc
        {
            inventoryOption();
            gatherOption();
            recoverOption();
            viewClear();
        }

    }




}

Item.h 文件!

#include <string>

#pragma once

class Item
{
public:

    int getId();
    int getQuantity();
    std::string getName();

    void setQuantity(int set);

    Item(int id, std::string name);

private :

    int id;
    std::string name;
    int quantity;


};

Item::Item(int id, std::string name)
{
    Item::id = id;
    Item::name = name;

}
int Item::getQuantity()
{
    return quantity;
}
int Item::getId()
{
    return id;
}

std::string Item::getName()
{
    return name;
}

void Item::setQuantity(int set)
{
    quantity = set;
}

Inventory.h 头文件!

#include "Item.h"
#include <vector>
#include <iostream>

#pragma once

class Inventory
{
public:

    Inventory();
    std::vector<Item> inventory;
    void addItem(Item item);
    std::string display(Inventory inventory);






};
Inventory::Inventory()
{
}
void Inventory::addItem(Item item)
{
    int id = item.getId();
    boolean added = false;

    for (Item check : Inventory::inventory)
    {


        if (id == check.getId())
        {

            int x = check.getQuantity();
            x++;
            check.setQuantity(x);
            std::cout << "Check!" << check.getQuantity() << check.getName();
            added = true;

        }

    }
    if (!added)
    {
        item.setQuantity(0);
        Inventory::inventory.push_back(item);
    }

}





std::string Inventory::display(Inventory inventory)
{
    std::string display = "---Inventory---\n";
    display += "\n--------------------------------------\n";
    if (Inventory::inventory.size()== 0)
        return display;
    else
    {
        for (Item item : Inventory::inventory)
        {
            display += "     Name: " + item.getName();
            display += " Id: " + std::to_string(item.getId());
            display += " Quantity: " + std::to_string(item.getQuantity());
            display += "\n--------------------------------------\n";

        }


        return display;
    }
}

Answer 1

您的问题在这一行:

for (Item check : Inventory::inventory)

您修改了check，但check 是您库存中项目的拷贝!将 check 作为一个 reference 来循环:

for (Item &check : Inventory::inventory)
         ^^^

---

此外，当您第一次获得一个项目时，您将其数量设置为 0:

item.setQuantity(0);

这是故意的吗？也许您的意思是将其设置为 1:

item.setQuantity(1);

或者更好的是，在构造函数中添加一个集合为 1! (毕竟，当一件元素被制作出来时，是因为我们至少拥有其中一件，对吧？)。当你这样做的时候，你可以切换到你的构造函数的字段初始化列表，让生活更轻松:

Item::Item(int id, std::string name) : id(id), name(name), quantity(1) { }