ANTICHAT — форум по информационной безопасности, OSINT и технологиям

Односвязный список
info - тело несущее информацию
after - адрес следующего элемента

Двусвязный список
befor - адрес предидущего элемента
info - тело несущее информацию
after - адрес следующего элемента

#include <iostream>
#include <cstdlib>

#define length 20

void create(char filename[]);
void open(char filename[], struct s_item *item[]);
int find(struct s_item *item[]);

int add_item(struct s_item item, int position);
int del_item(int position);
int erase_item();
int show_items();

struct s_item
{
    int id;
    char name[length];
};

struct p_item
{
    struct s_item info;
    struct p_item *next;
};

struct p_item *first;
struct p_item *counter;

int main()
{
    system("chcp 1251");
    printf("\n");
    
    struct s_item item;

    char menu;
    char filename[length];
    int high;
    int size;
    int position;
    
    first = NULL;
    
    while(true)
    {
        printf("Введите номер действия :\n");
        printf("========================\n");
        printf("1 - Добавить\n");
        printf("2 - Вставить\n");
        printf("3 - Удалить\n");
        printf("4 - Очистить\n");
        printf("5 - Вывести\n");
        printf("6 - Выход\n\n");
        
        printf("Номер = "); scanf("%i", &menu);
        printf("\n");

        if (menu == 1 || menu == 2)
        {
            printf("Введите номер товара : ");        scanf("%i", &item.id);
            printf("Введите наименование товара : "); scanf("%s", &item.name);
            printf("\n");
        }


        switch(menu)
        {
            case 1:
                position = -1;
                add_item(item, position);
            break;

            case 2:
                printf("Введите позицию вставки : "); scanf("%i", &position);
                printf("\n");
                add_item(item, position);
            break;

            case 3:
                printf("Введите позицию удаления : "); scanf("%i", &position);
                printf("\n");
                del_item(position);
            break;

            case 4:
                erase_item();
            break;

            case 5:
                show_items();
            break;

            case 6:
                return EXIT_SUCCESS;
            break;

            default:
                return EXIT_SUCCESS;
            break;
        }
    }

    return EXIT_SUCCESS;
}

int erase_item()
{
    struct p_item *now;
    
    counter = first;
    
    while (counter != NULL)
    {
         now = counter->next;
         counter->next = NULL;
         
         free(counter);
         
         counter = now;
    }
    
    first = NULL;
}
  
int add_item(struct s_item item, int position)
{
    struct p_item *now;  
    struct p_item *tmp;
    
    now = (p_item *) malloc(sizeof(p_item));
    
    if (now == NULL)
    {
        printf("Not enough memory to allocate buffer\nProgramm halted...\n");
    } else {                       
        now->info = item;
        now->next = NULL;
        
        if (first == NULL)
        {
            first = now;
        } else {    
            switch (position)
            {
                case -1:
                    counter = first;

                    while (counter->next != NULL)
                    {
                        counter = counter->next;
                    }

                    counter->next = now;
                break;
                    
                case 0:
                    tmp = first;
                    first = now;
                    now = tmp;
                    first->next = now;
                    
                    printf("%i - %i = %i", first->next, now, now->next);

                break;

                default:
                    counter = first;

                    for (int i = 2; i <= position; i++)
                    {
                        counter = counter->next;

                        if (counter == NULL)
                        {
                            printf("Position not in array!\n");
                            return 0;
                        }
                    }

                    now->next = counter->next;
                    counter->next = now;
                break;
            }
            
            return 1;
        }
    }
    
    return 0;
}

int del_item(int position)
{
    struct p_item *now;

    if (first == NULL)
    {
        return 0;
    } else {    
        if (position > -1)
        {
            if (position == 0)
            {
                now = first;
                first = first->next;              
            } else {
                counter = first;
                now = counter->next;
    
                for (int i = 2; i <= position; i++)
                {
                    counter = counter->next;
                    now = counter->next;
                    
                    if (now == NULL)
                    {
                        printf("Position not in array!\n");
                        return 0;
                    }
                }
                
                counter->next = now->next;
                now->next = NULL;
            }
            
            free(now);
        } else {            
            counter = first;
            now = counter->next;
            
            while (now->next != NULL)
            {
                counter = counter->next;
                now = counter->next;
            }
            
            free(now);
            counter->next = NULL;
        }
        
        return 1;
    }
    
    return 0;
}

int show_items()
{
    counter = first;
    
    if (first == NULL)
    {
        printf("Записей нет!\n\n");
    } else {
        printf("Вывод товара\n");
        printf("=============\n");

        while(counter != NULL)
        {
            printf("Номер товара = %i\n", counter->info.id);
            printf("Наименование товара = %s\n",  counter->info.name);
            printf("\n");
            
            counter = counter->next;
        }
        
        printf("\n");
    }
}

class ListItem{
public:
    ListItem(int _data){
        data = _data;
        next = 0;
    };
    int data;
    ListItem* next;
};

class List{
public:
    void add(int data){
		getTail()->next = new ListItem(data);
		};
		
        
    bool find(int data);
    bool del(int data);
private:
	ListItem* getTail(){
		ListItem* item = head;
		while(item->next){
			item = item->next;
		}
		return item;
	};
	
    ListItem* head;
};