laba17

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <stdlib.h>
#include <windows.h>
#include <string.h>


struct list
{
    char* string= new char[128];
    list *next;
    list *prev;
};

FILE fill(FILE* file)
{
    rewind(file);
    char* string;
    string = new char[128];
    gets_s(string, 128);
    while (gets_s(string, 128), strlen(string) != 0)
    {
        fputs(string, file);
        fputs("\n", file);
    }
    delete[] string;
    return (*file);
}

FILE show(FILE* file)
{
    rewind(file);
    char* string;
    string = new char[128];
    while (fgets(string, 128, file) > 0)
        puts(string);
    delete[] string;
    return(*file);
}



void listprint(list* first)
{

    while (first != NULL)
    {
        puts(first->string);
        first = first->next;
    }
}
void list_delete(list *& head)
{
    list* q = head;
    while (head != NULL)
    {
        head = head->next;
        delete q;
        q = head;

    }

}
void fromfiletolist(FILE*file,list*&head,list*&tail)
{
    char* strfile;
    strfile = new char[128];
    rewind(file);
    list * now,*p;
    head = new list;
    fgets(strfile, 128, file);
    strcpy(head->string, strfile);
    head->next = NULL; // указатель на следующий узел
    head->prev = NULL; // указатель на предыдущий узел
    p = head;
    while (fgets(strfile, 128, file) > 0)
    {
        now = new list;
        strcpy(now->string, strfile);
        p->next = now;
        now->prev = p;
        p = p->next;
        p->next = NULL;
    }
    tail = p;

}
void sort(FILE* file, list*& head, list*& tail)
{
    rewind(file);
    int fl;
    list* n,*p,*q;
    char* strfile;
    strfile = new char[128];
    while (fgets(strfile, 128, file) > 0)
    {
            if (head == NULL) //формирование
            {
                head = new list;
                strcpy(head->string, strfile);
                head->next = NULL;
                head->prev = NULL;
                tail = head;
            }
            else
            {
                n = new list;
                strcpy(n->string, strfile);
                if (strlen(n->string) > strlen(head->string)) //вставка в начало списка
                {
                    n->next = head;
                    head->prev = n;
                    head = n;
                }
                else
                {
                    fl = 0;
                    p = head;
                    q = head;
                    while ((q = q->next) != NULL && !fl)
                    {
                        if (strlen(n->string) > strlen(q->string))//вставка n перед q
                        {
                            n->next = p->next;
                            q->prev = n->prev;
                            p->next = n;
                            q->prev = n;
                            fl = 1;
                        }
                        else p = q; //н после q
                    }
                    if (!fl)
                    {
                        n->next = NULL;
                        p->next = n;
                        n->prev = n;
                        tail = n;
                    }
                }
            }
        }

}

void task(list*& head, list*& tail)
{
    list* q;
    q = head->next;
    delete head;
    head = q;
    head->prev = NULL;
    q = tail->prev;
    delete tail;
    tail = q;
    tail->next = NULL;
}


int main()
{

    FILE* file;
    char* filename;
    filename = new char[30];
    puts("Input filename");
    gets_s(filename, 30);
    fopen_s(&file, filename, "r+");

    if (file == NULL)
    {
        int f;
        puts("file not found. Create new? 1-yes 0-no");
        scanf_s("%d", &f);
        if (f == 0)
            return(0);
        else
        {
            fopen_s(&file, filename, "w+");
            puts("input strings into the file");
            fill(file);
        }
    }
    puts("=====content of the file=====");
    show(file);//файл сформирован или прочитан
    list* tail=NULL;
    list* head = NULL;
    //fromfiletolist(file,head,tail);
    sort(file, head, tail);
    puts("=====formed and sorted list =====");
    listprint(head);
    task(head, tail);
    puts("=====new list =====");
    listprint(head);
    list_delete(head);
    puts("=====memory clear =====");
    listprint(head);
}