在C ++向量中修改对象值时遇到问题

Question

I am trying to develop an inventory system for a game in c++. I have 2 header files one is named item and the other inventory these are sent into my main method. The way I have my code set up is when I send an Item object to my inventory the inventory checks to see if an object with the same ID exists. If it does then get the quantity Item value and increment it by one. The problem is the change to the Quantity value does not save to the main Inventory object. Any and all help would be very appreciated. Also sorry if my code is bad! I am not going to include all the code, and I am sure that all the proper #include functions are in!

The real issue seems to be somewhere in the actual new Quantity value not being added to the main Inventory object.

#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 File!

#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 Header File!

#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

Your issue is in this line:

for (Item check : Inventory::inventory)

You modify check , but check is a copy of items in your inventory! Loop through with check being a reference instead:

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

---

Also, when you first get an item, you set its quantity to 0 :

item.setQuantity(0);

Is this intentional? Perhaps you mean to set it to 1 instead:

item.setQuantity(1);

Or even better, add a set to 1 in the constructor! (after all, when an item is made it's because we have at least one of it, right?). And while your at it, you can switch to a field initialization list with your constructors to make life easier as well:

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