C++ 将数据从文件读入多个类对象C++；

如何使用默认类构造函数创建多个新类对象

对于一个项目，我必须编写一个程序，将三个类对象写入一个文件。我所做的。。。下一部分是使用readData函数将数据读回三个单独的类对象，然后显示数据。我完全不知道该怎么做，所以readData函数中没有任何代码

下面是对象写入文件时的外观示例

employee name(21, "first last", "45 East State", "661-9000", 30, 12.00);

这是我的大部分代码employee类相当基本，但这里是默认的类构造函数

employee::employee ();
employee::employee(int locEmpNumber, string locName, string locaddress, string locphone, double locHrWorked, double locHrWage)



#include "employee.h" 
#include <string>
#include <iomanip>
#include <iostream>
#include <fstream>
using namespace std;

void writeData (const employee& e);
void readData (const employee& e);
void printCheck (const employee& e);


int main( )
{
//Declarations
const int ONE = 1;
const int TWO = 2;

int userInput;

cout << "This program has two options:" << endl;
cout << "1 - Create a data files called 'EmployeeInfo.txt', or" << endl;
cout << "2 - Read data from a file and print paychecks." << endl;
cout << "Please enter (1) to create a file or (2) to print checks: ";

cin >> userInput;

if (userInput == ONE)
{
    //Create employee objects:
    employee joe(37, "Joe Brown", "123 Main St.", "123-6788", 45, 10.00);
    employee sam(21, "Sam Jones", "45 East State", "661-9000", 30, 12.00);
    employee mary(15, "Mary Smith", "12 High Street", "401-8900", 40, 15.00);

    ofstream empFile ("EmployeeInfo.txt");

    //Employee objects to write themselves out to the file.
    writeData(joe);
    writeData(sam);
    writeData(mary);

    //Close the file.
    empFile.close();

    //Print an message that creation of the file is complete.
    system("CLS");
    cout << "\nCreation of 'EmployeeInfo.txt' has completed.\n";
    cout << "\nYou can now run option 2.\n";

    //Exit.
    system("PAUSE");
    return 0;
}
else if (userInput == TWO)
{
    //Create three new Employee objects, using the default Employee constructor.

    //Open the file that you just saved.

    //Have each object read itself in from the file.

    //Call the printCheck( ) function for each of the three new objects, just as you did in the previous project.
}
else
{
    system("CLS");      
    cout << "Incorrect entry.... Please try again and follow directions closely! \n" << endl;
    system("PAUSE");
    return 0;
}


}

void writeData(const employee& e)
{
fstream empFile;
empFile.open ("EmployeeInfo.txt", ios::app);

empFile << e.getEmpNumber() << "\n";
empFile << e.getName() << "\n";
empFile << e.getAddress() << "\n";
empFile << e.getPhone() << "\n";
empFile << e.getHrWorked() << "\n";
empFile << e.getHrWage() << "\n";
}

void readData(const employee& e)
{
fstream empFile;    
empFile.open ("EmployeeInfo.txt", ios::in);

if(empFile.fail())
{
    cout << "File could not be open. Please try option 1 then option 2.\n" << endl; 
    return;
}

}

employee:：employee（）；
employee:：employee（int locEmpNumber、string locName、string locaddress、string locphone、double locHrWorked、double locHrWage）
#包括“employee.h”
#包括
#包括
#包括
#包括
使用名称空间std；
无效书面数据（施工人员和设备）；
无效读取数据（const employee&e）；
作废打印检查（施工人员和设备）；
int main（）
{
//声明
常数int ONE=1；
常数int 2=2；
int用户输入；
cout很高兴看到您已经努力解决了这个问题。但是，您在问题中提出的内容与代码中的一些注释之间存在不匹配。我似乎很清楚，您的摘要的一个关键部分是employee对象本身需要能够将自身写入文件并读取自身从文件中

您已经编写了将对象内容写入文件的代码，而不是让对象将自身写入文件。这看起来像是在吹毛求疵，但这就是面向对象编程的本质。将功能封装在对象本身中才是真正的目标

我在下面提供了一些代码来帮助您。希望这对您有意义

class employee
{
private:
    int _locEmpNumber;
    std::string _locName;
    std::string _locAddress;
    std::string _locPhone;
    double _locHrWorked;
    double _locHrWage;

public:
    employee();
    employee(int locEmpNumber, std::string locName, std::string locAddress, std::string locPhone, double locHrWorked, double locHrWage);

    //object should be able to save itself as per your project brief.
    void writeData(std::ofstream &empFile);

    //object should be able to read itself from file as per your project brief
    void readData(std::ifstream &empFile);
};

employee::employee()
{
    _locEmpNumber = 0;
    _locHrWorked = _locHrWage = 0;
}


employee::employee(int locEmpNumber, std::string locName, std::string locAddress, std::string locPhone, double locHrWorked, double locHrWage)
{
    _locEmpNumber = locEmpNumber;
    _locName = locName;
    _locAddress = locAddress;
    _locPhone = locPhone;
    _locHrWorked = locHrWorked;
    _locHrWage = locHrWage;
}

//
//From what I can glean from your brief ...
//Employee objects to write themselves out to the file!!!
void employee::writeData(std::ofstream &empFile)
{
    empFile << _locEmpNumber << std::endl;
    empFile << _locName << std::endl;
    empFile << _locAddress<< std::endl;
    empFile << _locPhone << std::endl;
    empFile << _locHrWorked << std::endl;
    empFile << _locHrWage << std::endl;
}

//
//Again, from what I can glean from your brief ...
//Have each object read itself in from the file!!!
void employee::readData(std::ifstream &empFile)
{
    //Normally you would have error handling in a method like this and
    //would either return a response that indicates that the operation
    //succeded or failed. You might alternatively use exception handling
    //or indeed a combination of both.
    //
    //Normally you would reset all members to initial / empty values before
    //reading values into them from your file. In this case we will omit that
    //for the purposes of simplicity. The main reason you would reset members
    //is to ensure that when reusing an object you don't end up with partial
    //data from the current "read" operation mixed with partial data that
    //was already in the object before you started reading.
    std::string inputStr;
    std::getline(empFile, inputStr);
    _locEmpNumber = atoi(inputStr.c_str());
    std::getline(empFile, _locName);
    std::getline(empFile, _locAddress);
    std::getline(empFile, _locPhone);
    std::getline(empFile, inputStr);
    _locHrWorked = atof(inputStr.c_str());
    std::getline(empFile, inputStr);
    _locHrWage = atof(inputStr.c_str());
}


int main(int argc, char* argv[])
{
    //Declarations
    const int ONE = 1;
    const int TWO = 2;

    int userInput;

    std::cout << "This program has two options:" << std::endl;
    std::cout << "1 - Create a data files called 'EmployeeInfo.txt', or" << std::endl;
    std::cout << "2 - Read data from a file and print paychecks." << std::endl;
    std::cout << "Please enter (1) to create a file or (2) to print checks: ";

    std::cin >> userInput;

    if (userInput == ONE)
    {
        //Create employee objects:
        employee joe(37, "Joe Brown", "123 Main St.", "123-6788", 45, 10.00);
        employee sam(21, "Sam Jones", "45 East State", "661-9000", 30, 12.00);
        employee mary(15, "Mary Smith", "12 High Street", "401-8900", 40, 15.00);

        std::ofstream empFile ("EmployeeInfo.txt");

        //Employee objects to write themselves out to the file.
        joe.writeData(empFile);
        sam.writeData(empFile);
        mary.writeData(empFile);
//      writeData(joe);
//      writeData(sam);
//      writeData(mary);

        //Close the file.
        empFile.close();

        //Print an message that creation of the file is complete.
        system("CLS");
        std::cout << "\nCreation of 'EmployeeInfo.txt' has completed.\n";
        std::cout << "\nYou can now run option 2.\n";

        //Exit.
        system("PAUSE");
        return 0;
    }
    else if (userInput == TWO)
    {
        //Create three new Employee objects, using the default Employee constructor.
        employee joe;
        employee sam;
        employee mary;

        //Open the file that you just saved.
        std::ifstream empFile("EmployeeInfo.txt");

        //Have each object read itself in from the file.
        joe.readData(empFile);
        sam.readData(empFile);
        mary.readData(empFile);

        empFile.close();

        //Call the printCheck( ) function for each of the three new objects, just as you did in the previous project.

        //I'll leave it to you to add this yourself.
    }
    else
    {
        system("CLS");      
        std::cout << "Incorrect entry.... Please try again and follow directions closely! \n" << std::endl;
        system("PAUSE");
        return 0;
    }
    return 0;
}

class员工
{
私人：
国际地点编号；
std:：string\u locName；
std：：字符串地址；
std:：string_locPhone；
双罗氏加工；
双倍工资；
公众：
雇员（）；
员工（int LOCEMPNAME，std:：string locName，std:：string locAddress，std:：string locPhone，双locHrWorked，双locHrWage）；
//对象应该能够根据您的项目摘要保存自身。
void writeData（std:：ofstream&empFile）；
//对象应该能够根据项目概要从文件中读取自身
void readData（std:：ifstream和empFile）；
};
雇员：：雇员（）
{
_LOCEMPNAME=0；
_locHrWorked=_locHrWage=0；
}
employee:：employee（int locEmpNumber，std:：string locName，std:：string locAddress，std:：string locPhone，double locHrWorked，double locHrWage）
{
_LOCEMPNAME=LOCEMPNAME；
_locName=locName；
_locAddress=locAddress；
_locPhone=locPhone；
_locHrWorked=locHrWorked；
_locHrWage=locHrWage；
}
//
//从你的简报中我能收集到。。。
//员工对象将自己写入文件！！！
void employee:：writeData（std:：ofstream&empFile）
{
empFile欢迎使用StackOverflow！为了更好地回答您的问题，通常建议您提供一个关于问题的最小示例。因此，尽可能地分解代码。发布大块代码很可能会吓跑潜在的帮助者。请参阅sscce.org