c++ - 对指针 vector 进行排序工作一次然后崩溃 "unable to read memory"

Question

我有一个 Flight pointers vector ，我将它传递给一个函数，以便在屏幕上进行排序和显示。我在 Flight 类 中使用仿函数来进行排序。它第一次运行完美，然后在 sortCriteria 递增后，它在第二次尝试单步执行航类 vector 时崩溃。 我得到的错误是 Access violation reading location 0x013DFFFC，所以我打赌这与 vector 在第一次排序后失去对内存位置的跟踪有关。提前感谢您提供的任何帮助。 这是我的排序功能:

//this function displays the flight schedule and sorts it by any field
void showFlightSchedule(vector<Flight*>& flights)
{
    //declare local variables
    char choice = ' ';
    int sortCriteria = 1;
while (toupper(choice) != 'X')
{
    //choosing which field to sort the schedule by
    switch (sortCriteria)
    {
    case 1:
        sort (flights.begin(), flights.end(), Flight::SortByDepartCity);
        break;
    case 2:
        sort (flights.begin(), flights.end(), Flight::SortByDestinationCity);
        break;
    case 3:
        sort (flights.begin(), flights.end(), Flight::SortByDepartTime);
        break;
    case 4:
        sort (flights.begin(), flights.end(), Flight::SortByArrivalTime);
        break;
    case 5:
        sort (flights.begin(), flights.end(), Flight::SortByFlightNumber);
        break;
    case 6:
        sort (flights.begin(), flights.end(), Flight::SortByAircraftType);
        break;
    case 7:
        sort (flights.begin(), flights.end(), Flight::SortByFreqFlyPoints);
        break;
    case 8:
        sort (flights.begin(), flights.end(), Flight::SortByFlightFull);
        break;
    }


    //display header
    system("cls");
    cout << left << endl;
    cout << "     " << setw(7) << "From" << setw(6) << "To" << setw(8) << "Depart" << setw(8) << "Arrive" <<
        setw(8) << "Flight" << setw(12) << "Aircraft" << setw(12) << "Frequent" << setw(6) << "Flight\n";
    cout << "\t\t\t\t  " << setw(10) << "Number" << setw(8) << "Type" << setw(14) << "Flyer Points" << setw(6) << "Status\n";

    //slightly altering the header to indicate how the list is sorted
    switch (sortCriteria)
    {
    case 1:
        cout << "   --\\_/------------------------------------------------------------------\n\n";
        break;
    case 2:
        cout << "   ---------\\_/-----------------------------------------------------------\n\n";
        break;
    case 3:
        cout << "   ----------------\\_/----------------------------------------------------\n\n";
        break;
    case 4:
        cout << "   ------------------------\\_/--------------------------------------------\n\n";
        break;
    case 5:
        cout << "   --------------------------------\\_/------------------------------------\n\n";
        break;
    case 6:
        cout << "   -----------------------------------------\\_/---------------------------\n\n";
        break;
    case 7:
        cout << "   -----------------------------------------------------\\_/---------------\n\n";
        break;
    case 8:
        cout << "   ----------------------------------------------------------------\\_/----\n\n";
        break;
    }

    //step through the flights vector displaying the information
    for (int idx = 0; idx < flights.size(); idx++)
    {
        cout << "     " << setw(7) << flights[idx]->getDepartCity() << setw(6) << flights[idx]->getDestinationCity() << setw(8) <<
            flights[idx]->getDepartTime() << setw(9) << flights[idx]->getArrivalTime() << setw(10) << flights[idx]->getFlightNumber() << setw(11) <<
            flights[idx]->getAircraftType() << setw(11) << flights[idx]->getFreqFlyPoints();
        if (flights[idx]->getFlightFull())
            cout << setw(6) << "FULL\n\n";
        else
            cout << endl << endl;
        flights[idx]++;
    }

    //display footer
    cout << "   -----------------------------------------------------------------------\n\n";
    cout << "\t\t\t  C -- Change Sorting\n";
    cout << "\t\t\t  X -- Exit to Main Menu\n";
    cout << "\t\t\t  Enter C or X: ";

    //get choice from user
    cin >> choice;

    //error-trapping loop
    while ((toupper(choice) != 'C') && (toupper(choice) != 'X'))
    {
        cout << "Please choose \"C\" or \"X\": ";
        cin >> choice;
    }

    //changing the sort flag
    if (sortCriteria == 8)
        sortCriteria = 1;
    else
        sortCriteria++;     
}

}

在我的 Flight.h 文件中，我有这些排序语句:

static bool SortByDepartCity(const Flight* f1, const Flight* f2)
{
    return f1->departCity < f2->departCity;
}

static bool SortByDestinationCity(const Flight* f1, const Flight* f2)
{
    return f1->destinationCity < f2->destinationCity;
}

static bool SortByDepartTime(const Flight* f1, const Flight* f2)
{
    return f1->departTime < f2->departTime;
}

static bool SortByArrivalTime(const Flight* f1, const Flight* f2)
{
    return f1->arrivalTime < f2->arrivalTime;
}

static bool SortByFlightNumber(const Flight* f1, const Flight* f2)
{
    return atoi(f1->flightNumber.c_str()) < atoi(f2->flightNumber.c_str());
}

static bool SortByAircraftType(const Flight* f1, const Flight* f2)
{
    return f1->aircraftType < f2->aircraftType;
}

static bool SortByFreqFlyPoints(const Flight* f1, const Flight* f2)
{
    return f1->freqFlyPoints > f2->freqFlyPoints;
}

static bool SortByFlightFull(const Flight* f1, const Flight* f2)
{
    return f1->flightFull < f2->flightFull;
}

Answer 1

删除这个

flights[idx]++;

在打印循环的最后一行。

附言这里有一些代码可以简化你的代码

template< class T, class FieldType, FieldType T::*FieldPtr >
struct LessBy {
    bool operator()( const T * left, const T * right ) const {
        return left->*FieldPtr < right->*FieldPtr;
    }
};

typedef LessBy< Flight, std::string, & Flight::departCity > SortByDepartCity;
typedef LessBy< Flight, std::string, & Flight::destinationCity > SortByDestinationCity;
//and so on