C++遍历类对象数组时出现溢出问题求助

使用范围for循环遍历PayRoll类对象数组，调用类函数修改double类型成员时出现负溢出问题。推测问题源于循环中操作的是数组对象的副本而非原数组，需要用指针或引用修复，但不知如何实现，希望用已学的简单方案解决。

PayRoll.h #

#pragma once
#include <string>

#include <iostream>
using namespace std;
class PayRoll
{
private:
    double payRate;
    double hoursWorked;

public:
    // Public member to allow outside functions to access employee names
    string name;
    
    //Constructor
    PayRoll(string, double, double);

    void setHoursWorked(double);

    double getGrossPay() const
    {
        double grossPay;
        grossPay = hoursWorked * payRate;
        cout << hoursWorked << endl;
        cout << payRate << endl;
        cout << grossPay << endl;
        return grossPay;
    }
};

PayRoll.cpp #

#include "PayRoll.h"
#include <string>
using namespace std;
// Constructor
PayRoll::PayRoll(string employee, double rate, double hours)
{
    name = employee;
    payRate = rate;
    hoursWorked = hours;
}

// Function to set hours worked
void PayRoll::setHoursWorked(double hours)
{
    hoursWorked = hours;
}

main.cpp #

#include <iostream>
#include "PayRoll.h"
#include <iomanip>
using namespace std;
int main()
{
    // Initializing an array of PayRoll objects
    const int NUMEMPLOYEES = 7;
    PayRoll employees[NUMEMPLOYEES] = {
                                        {"Annie", 15.50, 0},
                                        {"Bob", 14.75, 0},
                                        {"Callie", 18.65, 0},
                                        {"Derick", 18.65, 0},
                                        {"Evelyn", 22.45, 0},
                                        {"Frankie", 22.65, 0},
                                        {"Gertrude", 25.45, 0},
                                    };

    cout << "Please enter the hours worked by each employee." << endl;

    // Prompts the user to enter hours worked for each employee
    //ISSUE MAY BE STEMMING FROM HERE, USE A POINTER INSTEAD OF A COPY
    for (PayRoll person : employees)
    {
        cout << "How many hours did " << person.name << " work this week?" << endl;
        double hours;
        cin >> hours;
        while (hours < 0 || hours >60)
        {
            cout << "Please enter a number of between 0 and 60 for the week." << endl;
            cin >> hours;
        }
        person.setHoursWorked(hours);
    }

    // Displays all the employees' gross pay
    //ISSUE MAY BE STEMMING FROM HERE, USE A POINTER INSTEAD OF A COPY
    cout << endl << "Here is what everyone earned this week." << endl << endl;
    for (PayRoll person : employees)
    {
        cout << person.name << " earned $" << setprecision(2) << fixed << person.getGrossPay() << endl;
    }

    return 0;
}

你的推测完全正确：范围for循环中PayRoll person : employees会创建数组中每个对象的副本，修改副本的成员变量不会影响原数组里的对象。最终计算工资时，原对象的hoursWorked还是初始值0，出现的负溢出数值大概率是输出时的异常显示，核心问题是副本导致的修改无效。

最简单的修复方案是将范围for循环的变量改为引用，这样操作的就是原数组中的对象：

1. 修改输入小时数的循环：

for (PayRoll& person : employees)  // 添加&，将变量改为原对象的引用
{
    cout << "How many hours did " << person.name << " work this week?" << endl;
    double hours;
    cin >> hours;
    while (hours < 0 || hours >60)
    {
        cout << "Please enter a number of between 0 and 60 for the week." << endl;
        cin >> hours;
    }
    person.setHoursWorked(hours);
}

2. 修改显示工资的循环（用const引用更高效，避免不必要的拷贝，且符合只读操作的语义）：

for (const PayRoll& person : employees)  // 使用const引用
{
    cout << person.name << " earned $" << setprecision(2) << fixed << person.getGrossPay() << endl;
}

修改后，输入的小时数会直接作用于原数组中的对象，计算工资时就能得到正确结果，异常数值问题也会随之解决。

内容的提问来源于stack exchange，提问作者Fate