c++ - C++的初学者。帮助将结构传递给功能…？

嗨，初学者程序员在这里:]甚至不知道如何表达这个问题。我正在做家庭作业，似乎无法更改我创建的此结构的值(budget2)。

该程序的目标是显示第一个结构budget1，并在用户输入budget2的值后找到它与budget2之间的差异。

根据调试器的说明，当我使用inputData函数输入它们时，我并没有更改budget2中的任何值，因此，当showDiff函数运行时，它仅从budget1中减去budget2中的每个值，使所有总计显示为0。

#include <iostream>
#include <windows.h>
#include <string>

using namespace std;


struct MonthlyBudget
{
    MonthlyBudget();
    double housing, utilities, householdExpenses, transportation, food, medical, insurance, entertainment, clothing, misc;

};


int main()
{
    HANDLE screen = GetStdHandle(STD_OUTPUT_HANDLE);
    COORD position;

    void inputData(struct MonthlyBudget data);
    void displayData(struct MonthlyBudget);
    void showDiff(struct MonthlyBudget, struct MonthlyBudget);
    struct MonthlyBudget budget1, budget2;


    displayData(budget1);
    inputData(budget2);
    showDiff(budget1, budget2);




    system ("PAUSE");
    return 0;
}

MonthlyBudget::MonthlyBudget()
{
    housing = 500.00;
    utilities = 150.00;
    householdExpenses = 65.00;
    transportation = 50.00;
    food = 250.00;
    medical = 30.00;
    insurance = 100.00;
    entertainment = 150.00;
    clothing = 75.00;
    misc = 50.00;
}

void displayData(struct MonthlyBudget data)
{
    cout << "\n\tBudget\n\n\t";
    cout << "$" << data.housing << "\n\n\t";
    cout << "$" << data.utilities << "\n\n\t";
    cout << "$" << data.householdExpenses << "\n\n\t";
    cout << "$" << data.transportation << "\n\n\t";
    cout << "$" << data.food << "\n\n\t";
    cout << "$" << data.medical << "\n\n\t";
    cout << "$" << data.insurance << "\n\n\t";
    cout << "$" << data.entertainment << "\n\n\t";
    cout << "$" << data.clothing << "\n\n\t";
    cout << "$" << data.misc << "\n\n\t";

}

void inputData(struct MonthlyBudget data)
{

    HANDLE screen = GetStdHandle(STD_OUTPUT_HANDLE);
    COORD position;

    position.X = 15;
    position.Y = 3;
    SetConsoleCursorPosition(screen, position);

    cin >> data.housing;
    position.Y = 5;
    SetConsoleCursorPosition(screen, position);

    cin >> data.utilities;
    position.Y = 7;
    SetConsoleCursorPosition(screen, position);

    cin >> data.householdExpenses;
    position.Y = 9;
    SetConsoleCursorPosition(screen, position);

    cin >> data.transportation;
    position.Y = 11;
    SetConsoleCursorPosition(screen, position);

    cin >> data.food;
    position.Y = 13;
    SetConsoleCursorPosition(screen, position);

    cin >> data.medical;
    position.Y = 15;
    SetConsoleCursorPosition(screen, position);

    cin >> data.insurance;
    position.Y = 17;
    SetConsoleCursorPosition(screen, position);

    cin >> data.entertainment;
    position.Y = 19;
    SetConsoleCursorPosition(screen, position);

    cin >> data.clothing;
    position.Y = 21;
    SetConsoleCursorPosition(screen, position);

    cin >> data.misc;
    position.Y = 23;
    SetConsoleCursorPosition(screen, position);

}


void showDiff(struct MonthlyBudget data, struct MonthlyBudget data2)
{
    HANDLE screen = GetStdHandle(STD_OUTPUT_HANDLE);
    COORD position;

    position.X = 20;
    position.Y = 3;
    SetConsoleCursorPosition(screen, position);

    cout << (data.housing - data2.housing);

    position.Y = 5;
    SetConsoleCursorPosition(screen, position);
    cout << (data.utilities - data2.utilities);


    position.Y = 7;
    SetConsoleCursorPosition(screen, position);
    cout << (data.householdExpenses - data2.householdExpenses);

    position.Y = 9;
    SetConsoleCursorPosition(screen, position);
    cout << (data.transportation - data2.transportation);

    position.Y = 11;
    SetConsoleCursorPosition(screen, position);
    cout << (data.food - data2.food);

    position.Y = 13;
    SetConsoleCursorPosition(screen, position);
    cout << (data.medical - data2.medical);

    position.Y = 15;
    SetConsoleCursorPosition(screen, position);
    cout << (data.insurance - data2.insurance);

    position.Y = 17;
    SetConsoleCursorPosition(screen, position);
    cout << (data.entertainment - data2.entertainment);

    position.Y = 19;
    SetConsoleCursorPosition(screen, position);
    cout << (data.clothing - data2.clothing);

    position.Y = 21;
    SetConsoleCursorPosition(screen, position);
    cout << (data.misc - data2.misc);

    position.X = 5;
    position.Y = 23;
    SetConsoleCursorPosition(screen, position);

}

不太确定我在做什么错，任何帮助将不胜感激。非常感谢你。

PS。我知道我的代码一定看起来很荒谬。

最佳答案

您正在按值传递结构。
这意味着无论何时调用函数之一，结构都会被复制，然后传递给函数。因此，在您的情况下，budget2被复制并传递给inputData。但是，完成inputData之后，budget2仍然与在副本上使用的功能相同。
您需要通过指针或引用传递您的结构。我希望在您的情况下使用引用。
因此，您的函数应如下所示:void inputData(MonthlyBudget& data);
顺便说一句:
您应该真正读一本有关c++的好书，并阅读有关按值传递或按引用传递的知识。