c++ - vector 的 undefined reference

Question

我在使用 vector 时得到一个 undefined reference 。

这里是错误:

/tmp/ccYnTr05.o: In function `TourManager::addCity(City)':
tsp.cpp:(.text._ZN11TourManager7addCityE4City[TourManager::addCity(City)]+0x1c): undefined reference to `TourManager::destinationCities'
/tmp/ccYnTr05.o: In function `TourManager::getCity(int)':
tsp.cpp:(.text._ZN11TourManager7getCityEi[TourManager::getCity(int)]+0x14): undefined reference to `TourManager::destinationCities'
/tmp/ccYnTr05.o: In function `TourManager::numberOfCities()':
tsp.cpp:(.text._ZN11TourManager14numberOfCitiesEv[TourManager::numberOfCities()]+0x5): undefined reference to `TourManager::destinationCities'
collect2: ld returned 1 exit status

这是代码片段:

class TourManager
{
private:

    static vector<City> destinationCities;

public:

    static void addCity(City city)
    {
        destinationCities.push_back(city);
    }

    static City getCity(int index)
    {
        return (City)destinationCities.at(index);
    }

    static int numberOfCities()
    {
        return (int)destinationCities.size();
    }
};

我意识到vector还没有被初始化为一个值，但是vectors不是动态分配内存吗？我不确定如何解决这个未定义的引用问题？是 vector 问题还是其他问题？谢谢。

Answer 1

您只将 vector 声明为静态数据成员，但您还需要在类外定义它。例如

vector<City> TourManager::destinationCities;