Сортировка односвязного списка

#include "stdafx.h"
#include <string>
#include <iostream>
#include <fstream>
#include <conio.h>
 
using namespace std;
 
struct Book {
    string author;
    string name;
    unsigned int year;
    unsigned int number;
    unsigned int pages;
    Book* next;
 
    Book (unsigned int Number, unsigned int Pages, unsigned int Year, string Name = "unknown", string Author = "unknown") {
        next = 0;
        if (!Author.empty ()) {
            author = Author;
        }
        else {
            author = "unknown";
        }
        if (!Name.empty ()) {
            name = Name;
        }
        else {
            name = "unknown";
        }
        year = Year;
        number = Number;
        pages = Pages;
    }
};
 
struct Library {
    Book* first;
 
    Library (void) {
        first = 0;
    }
 
    ~Library (void) {
        for (;first != 0;) {
            Book* next = first->next;
            delete first;
            first = next;
        }
    }
 
    void addBook (Book* newBook) {
        if (first != 0) {
            Book* buffer = first;
            for (;;) {
                if (buffer->next != 0) {
                    buffer = buffer->next;
                }
                else {
                    buffer->next = newBook;
                    break;
                }
            }
        }
        else {
            first = newBook;
        }
    }
 
    void showBooks (unsigned int Pages = 0) {
        Book* current = first;
        for (;current != 0;) {
            unsigned int pages = current->pages;
            
            if (pages > Pages)  {
                cout << "Number: " << current->number << endl;
                cout << "Author: " << current->author << endl;
                cout << "Name: "   << current->name   << endl;
                cout << "Year: "   << current->year   << endl;
                cout << "Pages: "  << pages           << endl;
                cout<<"========================="<<endl;
            
                ofstream file("file.txt", ios::out );
            {   file<<current->number<< endl;
                file<<current->author<< endl;
                file<<current->name<< endl;
                file<<current->year<< endl;
                file<<pages<< endl;
                file<<"========================="<<endl;
            }
            }
            
            
            current = current->next;        
 
 
        }
        
        
 
        _getch ();
    }
 
    void showYear (unsigned int Year = 0)
    {
        Book* current = first;
        for (;current != 0;) {
            unsigned int year = current->year;
            if ((year == Year || Year == 0)) {
                cout << "Number: " << current->number << endl;
                cout << "Author: " << current->author << endl;
                cout << "Name: "   << current->name   << endl;
                cout << "Year: "   << year            << endl;
                cout << "Pages: "  << current->pages  << endl;
                cout<<"========================="<<endl;
            }
            current = current->next;
    }
        _getch ();
    }
 
    void deleteBooksByAuthor (string author) {
        Book* current = first;
        Book* prefered = first;
        for (;current != 0;) {
            if (current->author.compare (author) == 0) {
                if (prefered != current) {
                    prefered->next = current->next;
                }
                else {
                    prefered = current->next;
                    first = current->next;
                }
                delete current;
                current = prefered;
            }
            else {
                prefered = current;
                current = current->next;
            }
        }
    }
 
 //Вот сортировка тут тупик( //
    /* void showSortedBooksByYear (string author) {   
        Book* current = first;
        Book* currentMin = first;
        Book* currentFind = 0;
        bool searchStatus = true;
 
        
    }*/
};
 
 
void menuAddBook (Library* library) {
    int n;
 
        cout<<"Enter kol-vo vodimih khig: ";
        cin>>n;
        cout<<"--------------------------"<<endl;
 
  for(int i=0;i<n;i++)
  {
    cout << "Enter Number: ";
    unsigned int number;
    cin >> number;
    cout << "Enter Author: ";
    string author;
    cin >> author;
    cout << "Enter Name: ";
    string name;
    cin >> name;
    cout << "Enter Year: ";
    unsigned int year;
    cin >> year;
    cout << "Enter Pages: ";
    unsigned int pages;
    cin >> pages;
    cout<<"========================="<<endl;
    Book* newBook = new Book (number, pages, year, name, author);
    library->addBook (newBook);
  }
}
 
void menuShowAllBooks (Library* library) {
    library->showBooks ();
}
 
void menuDeleteBooksByAuthor (Library* library) {
    cout << "Enter author: ";
    string author;
    cin >> author;
    cout<<"--------------------------"<<endl;
    library->deleteBooksByAuthor (author);
}
 
void menuShowBooksByPages (Library* library) {
    cout << "Enter number of pages: ";
    unsigned int pages;
    cin >> pages;
    cout<<"--------------------------"<<endl;
    library->showBooks (pages);
}
 
void menuShowBooksByYear (Library* library) {
    cout << "Enter year: ";
    unsigned int year;
    cin >> year;
    cout<<"--------------------------"<<endl;
    library->showYear (year);
}
 
/*void menuShowBooksSortedByYear (Library* library) {
    cout << "Enter author: ";
    string author;
    cin >> author;
    library->showSortedBooksByYear (author);
}*/
 
void menuExit (Library* library) {
    cout << "Thank's for using.";
    _getch ();
    delete library;
    exit (0);
}
 
int main (void) {
    Library* library = new Library ();
 
    Book* book1 = new  Book (1,352,1837,"Pushkin A.S.","Evgeniy Onegin");
    Book* book2 = new  Book (2,144,1825,"Pushkin A.S.","Boris Godunov");
    Book* book3 = new  Book (3,167,1840,"Lermontov M.Y.","Geroy nashego vremeni");
    Book* book4 = new  Book (4,208,1835,"Lermontov M.Y.","Maskarad");
 
    library->addBook(book1);
    library->addBook(book2);
    library->addBook(book3);
    library->addBook(book4);
 
    while (true) {
    int m=0;
    system ("cls");  //*Очистка экрана*//
    cout<<"Function 1: dobavlenie el-tov"<<"                                         "<<"Enter - 1"<<endl;
    cout<<"Function 2: nachalnoe formirovanie dan-h o vseh knigah"<<"                "<<"Enter - 2"<<endl;
    cout<<"Function 3: ydalenie dan-h o knigah zadan-h avtorov "<<"                  "<<"Enter - 3"<<endl;
    cout<<"Function 4: vidacha dan-h o knigah s zadan-m godom izdaniya "<<"          "<<"Enter - 4"<<endl;
    cout<<"Function 5: sortirovka knig danogo avtora po polyu god izdaniya "<<"      "<<"Enter - 5"<<endl;
    cout<<"Function 6: poisk knig s kol-vom stranic > zadan-h "<<"                   "<<"Enter - 6"<<endl;
    cout<<"!Exit!"<<"                                                                "<<"Enter - 0"<<endl;
    cout<<"--------------------------------------------------------------------------------";
 
    cin>>m;
    cout<<"--------------------------------------------------------------------------------";
 
        switch(m)
        {
            case 1 : menuAddBook (library); break;
            case 2 : menuShowAllBooks (library); break;
            case 3 : menuDeleteBooksByAuthor (library); break;
            case 4:  menuShowBooksByYear (library);break;
        /*  case 5 : menuShowBooksSortedByYear (library); break;*/
            case 6 : menuShowBooksByPages (library); break;
            case 0 : menuExit (library); break;
            default: cout<<"!Error! - Enter numbers 0-6!";
        }
    }
 
}

void Library::sortByYear(){
bool run=true;
Book* cur;
Book* pre;
Book* endsort=NULL;
 while (run){
  cur=first;
  pre=NULL;
  run=false;
  while (cur->next!=endsort){
   if ( (cur->year) > (cur->next->year) ){
       pre->next=cur->next;
       cur->next=cur->next->next;
       pre->next->next=cur;
       run=true;
    }
   pre=cur;
   cur=cur->next;
  }
   endsort=cur;//если работает не так, удали к чёрту, 
                       //      пусть пузырь проходит N квадрат раз, зато надёжно
 }
}