C++ vector 问题 - 'LNK2001: unresolved external symbol private: static...'

Question

在有人指责我不查看预先存在的问题之前，我已经查看并意识到它与声明有关，但我仍然无法让它工作(可能与我使用 vector 有关)。

Manager.h:

#include "Flight.h"
#ifndef manager_h
#define manager_h

class Manager {
    static vector<Airport> airports;
    static vector<Flight> flights;
public:
    static void loadAirports();
    static void loadFlights();
    static Airport getAirport(string code);
    static vector<string> split(const string &s, vector<string> &elems);
};

#endif

Manager.cpp:

#include "Manager.h"

void Manager::loadAirports ()
{
    ifstream airportfile("airports.txt");
    string line;
    while (getline(airportfile, line))
    {
        vector<string> values;
        split(line, values);
        Airport airport (values[0], values[1], atoi(values[2].c_str()));
        airports.push_back(airport);
    }
}

void Manager::loadFlights ()
{
    ifstream flightfile("flights.txt");
    string line;
    while (getline(flightfile, line))
    {
        vector<string> values;
        split(line, values);
        Flight flight (getAirport(values[0]), getAirport(values[1]), atoi(values[2].c_str()), atoi(values[3].c_str()));
        flights.push_back(flight);
    }
    cout << flights.size() << endl;
}

Airport Manager::getAirport (string code)
{
    for (int i = 1; i < (int)airports.size(); i++)
    {
        if (airports[i].code == code)
            return airports[i];
    }
    throw exception();
}

vector<string> Manager::split(const string &s, vector<string> &elems) {
    stringstream ss(s);
    string item;
    while(getline(ss, item, ',')) {
        elems.push_back(item);
    }
    return elems;
}

它正在抛出这个错误:

Manager.obj : error LNK2001: unresolved external symbol "private: static struct Vector Manager::airports" (?airports@Manager@@0U?$Vector@UAirport@@@@A)

Manager.obj : error LNK2001: unresolved external symbol "private: static struct Vector Manager::flights" (?flights@Manager@@0U?$Vector@UFlight@@@@A)

我意识到我需要定义 vector ，但是如何以及在哪里？我尝试创建一个空的构造函数，然后做

Manager::Manager ()
{
    vector<string> flights;
    vector<string> airports;
}

但它只是给了我一个重新定义的错误。

Answer 1

您必须在 .cpp 文件中定义它们:

vector<string> Manager::flights;
vector<string> Manager::airports;