C++ LNK1120 Неразрешенный внешний элемент.Не понимаю как решить

Question

#define _CRT_SECURE_NO_DEPRECATE
#include<cstring>
#include <iostream>
#include <new>
#include<string>

using namespace std;

class Printed_edition
{
protected:
    static int N;
    char name[25];
    int page;
    char type[25];
    int i;
    Printed_edition* temp;
public:
    Printed_edition(void)
    {
        //N++;
        cout << "Counstructor without parameters!base!" << endl;
        page = 0;
        temp = this;
    }
    Printed_edition(const char* Name, const char* Type, int Value)
    {
        SetName(Name);
        SetType(Type);
        page = Value;
    }
    virtual ~Printed_edition(void)
    {
        cout << "Destructor" << endl;
    }
    virtual void show()
    {
        N = 0;
        for (i = 0; i < N; i++)
        {
            cout << temp->GetName() << endl;
        }
    }
    void SetName(const char Value[])
    {
        strcpy_s(name, Value);
    }
    void SetType(const char Value[])
    {
        strcpy_s(type, Value);
    }
    void SetPage(int Value)
    {
        page = Value;
    }
    char* GetName()
    {
        return name;
    }
    char* GetType()
    {
        return type;
    }
    int GetPage()
    {
        return page;
    }
};

class magazine : virtual public Printed_edition
{
public:
    magazine()
    {
        cout << "Counstructo without parameters" << endl;
        page = 0;
    }
    magazine(const char* Name,const char* Type, int Page)
    {
        strcpy_s(name, Name);
        strcpy_s(type, Type);
        page = Page;
    }
    magazine(const magazine& a)
    {
        cout << "Copying Constuctor" << endl;
        char *name = new char[strlen(a.name) + 1];
        strcpy(name, a.name);
        char *type = new char[strlen(a.type) + 1];
        strcpy(type, a.type);
        page = a.page;
    }
    virtual ~magazine()
    {
        cout << "Destructor" << endl;
    }

};
class book :virtual public Printed_edition
{
private:
    char genre[25];
public:
    book()
    {
        cout << "Constructor without parameters" << endl;
        page = 0;
    }
    book(const char* Name, const char* Type, int Page, const char* Genre)
    {
        strcpy_s(name, Name);
        strcpy_s(type, Type);
        page = Page;
        strcpy_s(genre, Genre);
    }
    book(const book& a)
    {
        cout << "Copying Constructor" << endl;
        char *name = new char[strlen(a.name) + 1];
        strcpy(name, a.name);
        page = a.page;
        char *type = new char[strlen(a.type) + 1];
        strcpy(type, a.type);
        char *genre = new char[strlen(a.genre) + 1];
        strcpy(genre, a.genre);
    }
    ~book()
    {
        cout << "Destructor" << endl;
    }
    void show()
    {
        for (i = 0; i < N; i++)
        {
            cout << temp->GetName() << endl;
        }
    }
    void SetGenre(const char GENRE[])
    {
        strcpy_s(genre, GENRE);
    }
    char* GetGenre()
    {
        return genre;
    }
};

class learning_book :virtual public Printed_edition, book
{
private:
    char lessontype[25];
public:
    learning_book()
    {
        cout << "Constructor wp" << endl;
        page = 0;
    }
    learning_book(const char* Name, const char* Type, int Page, const char* Lessontype)
    {
        cout << "Constructor with parameters" << endl;
        strcpy_s(name, Name);
        strcpy_s(type, Type);
        page = Page;
        SetLesson(Lessontype);
    }
    learning_book(const learning_book& a)
    {
        cout << "Copying Constructor" << endl;
        char *name = new char[strlen(a.name) + 1];
        strcpy(name, a.name);
        page = a.page;
        char *type = new char[strlen(a.type) + 1];
        strcpy(type, a.type);
        char *lessontype = new char[strlen(a.lessontype) + 1];
        strcpy(lessontype, a.lessontype);
    }
    ~learning_book()
    {
        cout << "Destructor" << endl;

    }
    /*void show()
    {
        if (i = 0; i < N; i++)
        {
            cout << temp->GetName() << endl;
        }
    }*/
    void SetLesson(const char* LT)
    {
        strcpy_s(lessontype, LT);
    }
    char *GetLessonType()
    {
        return lessontype;
    }
};


int main()
{
     //N = 0;
    magazine b1("Tall", "magazine", 12);
    system("pause");
}

Answer 1

Или исправить

static int N;

на

inline static int N;

или дописать за пределами класса определение

int Printed_edition::N;

(можно с инициализатором :)).

Ответ только на заданный вопрос, все остальные неприятности (а они есть, и еще какие!) проигнорированы.