基類繼承函數調用的派生類指針

Question

我試圖從.txt文件讀取數據，然後創建一個新的基類指針來存儲在一個向量中。我讀了數據，它都是正確的，但是當我將它傳遞給派生類的構造函數（它也轉到基類默認構造函數）時，它會拋出badptr和一個隨機數。我不知道我在哪裏出了問題，並且在這一點上花了幾個小時試圖調試它。我很感激任何幫助，試圖弄清楚。

即使在OneTime.cpp的構造函數中，我也設置了word =「test」，但它仍然沒有把它放在對象中。我也嘗試去掉OneTime構造函數，使用Appointment構造函數併發送變量無濟於事。

我可能做了一些愚蠢的事情......所以是的，任何幫助都會很棒。

這裏是我的代碼：

Test.cpp的

#include <fstream> 
#include "Monthly.h" 
#include "Appointment.h" 
#include "OneTime.h" 
#include "Daily.h" 

using namespace std; 
void main(){ 
    vector<Appointment*> appt; 

    string type; 
    string desc; 
    string apm; 
    int prio, dayz, mon, year, hour, min; 

    ifstream myfile("C:\\Users\\Computer\\Desktop\\Problem 2a\\ApptData.txt"); 

    while(!myfile.eof()){ 
     string temp; 
     getline(myfile, type, ':'); 
     getline(myfile, desc, ':'); 
     getline(myfile, temp, ':'); 
     prio = atoi(temp.c_str()); 
     getline(myfile, temp, ':'); 
     dayz = atoi(temp.c_str()); 
     getline(myfile, temp, ':'); 
     mon = atoi(temp.c_str()); 
     getline(myfile, temp, ':'); 
     year = atoi(temp.c_str()); 
     getline(myfile, temp, ':'); 
     hour = atoi(temp.c_str()); 
     getline(myfile, temp, ':'); 
     min = atoi(temp.c_str()); 
     getline(myfile, apm, '\n'); 

     if(type.compare("OneTime") == 0){ 
      Appointment* tempOneTime = new OneTime(desc, prio, year, mon, dayz, hour, min, apm); 
      appt.push_back(tempOneTime); 
      cout << "OneTime object created." << endl; 
     } 
     if(type.compare("Daily") == 0){ 
      Appointment* tempDaily = new Daily(desc, prio, year, mon, dayz, hour, min, apm); 
      appt.push_back(tempDaily); 
      cout << "Daily object created." << endl; 
     } 
     if(type.compare("Monthly") == 0){ 
      Appointment* tempMonthly = new Monthly(desc, prio, year, mon, dayz, hour, min, apm); 
      appt.push_back(tempMonthly); 
      cout << "Monthly object created." << endl; 
     } 
    } 
    myfile.close(); 
} 

Appointment.h

#include <string> 
using namespace std; 

#ifndef APPOINTMENT_H 
#define APPOINTMENT_H 

class Appointment{ 
public: 
    Appointment(); 
    Appointment(string desc, int priority, int year, int mon, int day, int hour, int min, string apm); 
    ~Appointment(); 

    virtual bool occursOn(int year, int mon, int day) = 0; 
    virtual void display() const; 

protected: 
    string desc; 
    int priority; 
    int year; 
    int mon; 
    int day; 
    int hour; 
    string apm; 
    int min; 
}; 
#endif 

Appointment.cpp

#include <string> 
#include <iostream> 
#include "Appointment.h" 

using namespace std; 

Appointment::Appointment(){ 
    string desc = "\n"; 
    int priority = 1; 
    int hour = 12; 
    int min = 0; 
    string ampm = "A.M.\n"; 
    int year = 1900; 
    int mon = 1; 
    int day = 1; 
} 

Appointment::Appointment(string word, int prio, int years, int month, int days, int hours, int minute, string apm){ 
    string desc = word; 
    int priority = prio; 
    int hour = hours; 
    int min = minute; 
    string ampm = apm; 
    int year = years; 
    int mon = month; 
    int day = days; 
} 

Appointment::~Appointment(){ 
} 

void Appointment::display() const{ 
    cout << this->desc << " at " << this->hour << ":" << this->min << " Priority: " << this->priority << endl; 
} 

OneTime.h

#ifndef ONETIME_H 
#define ONETIME_H 

#include "Appointment.h" 
#include <string> 

class OneTime : public Appointment{ 
public: 
    OneTime(); 
    OneTime(string desc, int priority, int year, int mon, int day, int hour, int min, string apm); 
    ~OneTime(); 

    virtual bool occursOn(int year, int mon, int day); 

protected: 
    string desc; 
    int priority; 
    int year; 
    int mon; 
    int day; 
    int hour; 
    string apm; 
    int min; 
}; 
#endif 

OneTime.cpp

#include <iostream> 
#include <string> 
#include "OneTime.h" 
using namespace std; 
OneTime::OneTime(){ 
    string desc = "\n"; 
    int priority = 1; 
    int hour = 12; 
    int min = 0; 
    string ampm = "A.M.\n"; 
    int year = 1900; 
    int mon = 1; 
    int day = 1; 
} 

OneTime::OneTime(string word, int prio, int years, int month, int days, int hours, int minute, string apm){ 
    word = "test"; 
    cout << "Word is equal to " << word; 
    string desc = "test"; 
    int priority = prio; 
    int hour = hours; 
    int min = minute; 
    string ampm = apm; 
    int year = years; 
    int mon = month; 
    int day = days; 
} 

OneTime::~OneTime(){ 
} 

bool OneTime::occursOn(int useryear, int usermon, int userday){ 
    if(this->day == userday && this->mon == usermon && this->year == useryear){ 
     return true; 
    } 
    else {cout << this->day;return false;} 
} 

Answer 1

您的代碼根本不會做你認爲它。藉此，例如：

Appointment::Appointment(){ 
    string desc = "\n"; 
    int priority = 1; 
    // ... 
} 

這並沒有初始化類Appointment的數據成員。這聲明瞭一堆局部變量，初始化它們，然後立即丟棄它們。數據成員保持未初始化狀態。創建它

Appointment::Appointment() 
    : desc("\n"), 
     priority(1) 
    // ... 
{} 

然後閱讀您最喜愛的C++教科書中的構造函數初始值設定項列表。以類似的方式修復代碼的其餘部分，作爲讀者的練習。

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哦，讓~Appointment()析構函數虛擬的，或者你以後有不同的問題。