Question

我已经做了一段时间了，现在可能只是变得糊里糊涂了。我是C ++的初学者，在调用delete删除数组中的元素时遇到了问题。它说调试断言失败了。在我的书和网络中，我发现他们正在做的就是我，所以我不确定为什么我会失败。有人可以帮忙吗？另外，我不反对一些改进提示。

#include <iostream>
#include <string>
#include <vector>
#include <fstream>
#include "Account.h"
#include "Person.h"
#include "Checkings.h"
#include "Savings.h"
#include "AccountException.h"
using namespace std;


void printAccountSummary(const vector<Account> &acc);
string TYPE;

int main()
{
    cout << "Project 3 - Greg Mora - 601\n" << endl;
    cout << "%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\n" << endl;
    cout << "The Avenger's Retirement Fund\n" << endl;
    cout << "#\tAccount Name \t\tAddress \t\tBalance\n" << endl;

    vector<Account*> acc;

    acc.push_back(new Savings(new Person("Bilbo Baggins", "43 Bag End"), 1, 500, 0.075));
    acc.push_back(new Checkings(new Person("Wizard Gandalf", "Crystal Palace"), 2, 1000.00, 2.00));
    acc.push_back(new Savings(new Person("Elf Elrond", "Rivendell"), 3, 1200, 0.050));

    ofstream dataOut("Accounts.txt");
    if (dataOut.bad())
        cout << "Error: File was unable to open." << endl;

    for (unsigned int i = 0; i < acc.size(); i++)
    {
        acc[i]->writeData(dataOut);
    }
    for (unsigned int i = 0; i < acc.size(); i++)
    {
        if (acc[i] != nullptr)
        {
            delete acc[i];
            acc[i] = nullptr;
        }
    }

    dataOut.close();
    acc.clear();

    try
    {
        ifstream dataInput;
        dataInput.open("Accounts.txt");
        if (dataInput.fail())
        {
            cout << "Error: File was unable to open." << endl;
        }

        while (!dataInput.eof())
        {
            getline(dataInput, TYPE);
            if (TYPE=="Savings")
            {
                Account* save = new Savings;
                save->readData(dataInput);
                acc.push_back(save);
            }
            else if (TYPE == "Checkings")
            {
                Account* check = new Checkings;
                check->readData(dataInput);
                acc.push_back(check);
            }
        }
    }
    catch (AccountException e)
    {
        dataOut.close();
        cout << e.getMessage();
        system("PAUSE");
        return 0;
    }

    for (unsigned int i = 0; i < acc.size(); i++)
    {
        acc[i]->makeWithdrawl(100.00);
    }
    for (unsigned int i = 0; i < acc.size(); i++)
    {
        acc[i]->makeDeposit(25.00);
    }

    for (unsigned int i = 0; i < acc.size(); i++)
    {
        cout << acc[i]->getAccountNumber() << "\t" << acc[i]->getPersonInfo()->getName() << "\t\t" <<
            acc[i]->getPersonInfo()->getAddress() << "\t\t" << acc[i]->getAccountBalance() << endl;
    }

    cout << endl << endl;
    system("PAUSE");
    return 0;
}

Person.cpp

#include "Person.h"
using namespace std;

Person::Person(){
    name = "";
    address = "";
}

Person::Person(string nameIn, string addressIn)
{
    name = nameIn;
    address = addressIn;
}

string Person::getName() const{
    return name;
}

string Person::getAddress() const{
    return address;
}

void Person::writeData(ofstream& output) const
{
    output << name << endl;
    if (output.bad())
    {
        throw AccountException("Unexpected error occurred during writing out of data");
    }
    output << address << endl;
    if (output.bad())
    {
        throw AccountException("Unexpected error occurred during writing out of data");
    }
}

void Person::readData(ifstream& input)
{
    getline(input, name);
    if (input.bad())
    {
        throw AccountException("Unexpected error occurred during reading in of data");
    }
    getline(input, address);
    if (input.bad())
    {
        throw AccountException("Unexpected error occurred during reading in of data");
    }
}

Account.cpp

#include "Account.h"
#include "Person.h"
#include "Checkings.h"
#include "Savings.h"
#include <iostream>
#include <string>
#include <fstream>
using namespace std;

Account::Account()
{
    accountNumber = 0;
    personInfo = nullptr;
    accountBalance = 0;
}

Account::Account(Person *personInfoIn, int accNumIn, double accBalIn)
{
    accountNumber = accNumIn;
    personInfo = personInfoIn;
    accountBalance = accBalIn;
}

int Account::getAccountNumber() const
{
    return accountNumber;
}

double Account::getAccountBalance() const{
    return accountBalance;
}

Person *Account::getPersonInfo() const{
    return personInfo;
}

void Account::makeDeposit(double depositAmt){
    accountBalance = accountBalance + depositAmt;
}

void Account::makeWithdrawl(double withdrawlAmt){
    accountBalance = accountBalance - withdrawlAmt;
}
Account::~Account(){
    if (personInfo != nullptr)
    {
        delete[] personInfo;
        personInfo = nullptr;
        accountBalance = 0;
        accountNumber = 0;
    }
}

Savings.cpp

#include "Savings.h"
#include "Account.h"
using namespace std;


Savings::Savings()
{
    accountBalance = 0;
    intRate = 0;    
}
Savings::Savings(Person *personInfoIn, int accNumIn, double accBalIn, double intRateIn)
:Account(personInfoIn, accNumIn, accBalIn)
{
    intRate = intRateIn;
}
double Savings::getAccountBalance() const
{
    return accountBalance + (accountBalance * intRate);
}
void Savings::readData(ifstream & input)
{
    personInfo = new Person;
    personInfo->readData(input);
    input >> accountNumber;
    if (input.bad())
    {
        throw AccountException("Unexpected error occurred during reading in of data");
    }
    input >> accountBalance;
    if (input.bad())
    {
        throw AccountException("Unexpected error occurred during reading in of data");
    }
    input.ignore();
}
void Savings::writeData(ofstream & output) const
{
    output << "Savings" << endl;
    personInfo->writeData(output);
    output << accountNumber << endl;
    if (output.bad())
    {
        throw AccountException("Unexpected error occurred during writing out of data");
    }
    output << getAccountBalance() << endl;
    if (output.bad())
    {
        throw AccountException("Unexpected error occurred during writing out of data");
    }
}

Checkings.cpp

#include "Checkings.h"
#include "Account.h"
using namespace std;


Checkings::Checkings()
{
    accountBalance = 0;
    monthlyFee = 0;
}
Checkings::Checkings(Person *personInfoIn, int accNumIn, double accBalIn, double monthlyFeeIn)
: Account(personInfoIn, accNumIn, accBalIn)
{
    monthlyFee = monthlyFeeIn;
}
double Checkings::getAccountBalance() const
{
    return accountBalance - monthlyFee;
}
void Checkings::readData(ifstream & input)
{
    personInfo = new Person;
    personInfo->readData(input);
    input >> accountNumber;
    if (input.bad())
    {
        throw AccountException("Unexpected error occurred during reading in checking account number");
    }
    input >> accountBalance;
    if (input.bad())
    {
        throw AccountException("Unexpected error occurred during reading in checking account balance");
    }
    input.ignore();
}
void Checkings::writeData(ofstream & output) const
{
    output << "Checkings" << endl;
    personInfo->writeData(output);
    output << accountNumber << endl;
    if (output.bad())
    {
        throw AccountException("Unexpected error occurred during writing out checking account number");
    }
    output << getAccountBalance() << endl;
    if (output.bad())
    {
        throw AccountException("Unexpected error occurred during writing out checking account balance");
    }
}

Answer 1

我看到的问题：

您正在使用operator new创建Person，但您正在使用operator delete []删除它。改变

Account::~Account(){
    if (personInfo != nullptr)
    {
        delete[] personInfo;   // Problem
        personInfo = nullptr;
        accountBalance = 0;
        accountNumber = 0;
    }
}

到

Account::~Account(){
    if (personInfo != nullptr)
    {
        delete personInfo;
        personInfo = nullptr;
        accountBalance = 0;
        accountNumber = 0;
    }
}

Answer 2

你在程序的早期有一个循环，你删除acc向量中的元素并将指针设置为nullptr，但是这不会从向量中删除元素。然后在程序结束时，您有三个循环遍历向量中的所有元素（包括您销毁的元素）并取消引用指针而不检查nullptr。

取消引用nullptr导致undefined behavior并且很可能导致您的崩溃。

可以想到两种可能的解决方案：在销毁循环之后清除向量，或在其他循环中添加nullptr的检查。

在删除指针向量时，调试断言失败了C ++

2 个答案: