header.h

#pragma once

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <conio.h>
#include <locale.h>

struct student
{
    char* name;
    char* surname;
    char* patronimyc;
    char letter;
    int year;
    int marks_numb;
    int *marks;
};

struct list
{
    struct student* stud;
    struct list* left;
    struct list* right;
};

int get_int();

char* get_string();

int get_year();

int get_positive();

int* get_ints(int size);

struct student* get_student();

struct student* student_delete(struct student* stud);

void student_print(struct student* stud);

int students_cmp(struct student* stud1, struct student* stud2);

void student_copy(struct student* source, struct student* destinition);

struct list* add_element(struct list* ring, struct student* stud);

struct list* move(struct list* el, char direction);

void show(struct list* ring, char direction);

struct list* search(struct list* head, struct student* stud);

struct list* delete_node(struct list* ring, struct student* stud);

void ring_free(struct list** ring);

void sort_by_value(struct list* head);

struct list* sort_by_pointer(struct list* head);

int choose();

void info();

void choose(struct list** ring, struct student* stud);