c++ - 调试断言失败。表达式映射迭代器不可取消引用

Question

我正在尝试通过迭代器删除对象，如下面的代码所示。该程序似乎在 ubuntu 上运行良好，但我现在在 visual studio 中，它抛出调试断言失败错误。表达式:映射/设置迭代器不可取消引用。

如有任何帮助，我们将不胜感激。

map<string, Booking*> bookings; // private variable

 /**
 * remove a booking from the passenger's booking map.
 * @param flightNumber string& - flight number of the booking to be removed.
 */
void Passenger::removeBooking(string& flightNumber)
{
    map<string, Booking*>::iterator it = bookings.find(flightNumber);
    bookings.erase(it);
    delete (*it).second; // <-- error occurs here
}

/**
 * add a booking to the passenger's booking map.
 * @param booking Booking& - the booking to be added.
 */
void Passenger::addBooking(Booking& booking)
{
    Booking* bookingPtr = new Booking(booking);
    bookings.insert(pair<string, Booking*>(booking.getFlightNumber(), bookingPtr));
}

/**
 * add a booking to the passenger's booking map.
 * @param flightNumber string& - flight number of the booking.
 * @param seat Seat::Type - seat type of the booking.
 * @param status Booking::Type - status of the booking.
 */
void Passenger::addBooking(string& flightNumber, Seat::Type seat, BookingStatus::Type status)
{
    Booking *bookingPtr = new Booking(flightNumber, seat, status);
    bookings.insert(pair<string, Booking*>(flightNumber, bookingPtr));
}

Answer 1

好的，现在代码已经完全从最初发布的代码改变...

错误很容易被发现。您正在从 map 中删除使迭代器无效的元素，然后您正在尝试使用该迭代器。在删除迭代器之前，您应该制作一份需要delete 的指针的临时拷贝，或者只是重新排列并先执行delete。

另外，正如评论中所建议的，您需要确保 find 返回的迭代器是有效的，即不等于 end()。

map<string, Booking*>::iterator it = bookings.find(flightNumber);
if (it != bookings.end())
{
    Booking* temp = it->second;
    bookings.erase(it);
    delete temp;
}

或

map<string, Booking*>::iterator it = bookings.find(flightNumber);
if (it != bookings.end())
{
    delete it->second;
    bookings.erase(it);
}