7

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <stdlib.h>
#include <time.h>

typedef struct _node* Position;
typedef struct _node
{
    int value;
    Position next;
}Node;

int PushStack(Position, int);
int PopStack(Position);
int AddFirst(Position, Position);
Position RandomValue(int);
void Print(Position);
int ArrayLength(Position);
void DeleteLast(Position);

int main(int argc, char** argv)
{
    Node stack;
    stack.next = NULL;
    int maxEl = 0;
    int choice = 0;
    srand((unsigned)time(NULL));


    printf("Circular stack maximum elements: ");
    scanf_s(" %d", &maxEl);
    printf("\r\n");

    while (choice != 4) {
        printf("1: push stack\r\n2: pop stack\r\n3: print list\r\n4: exit \r\n");
        printf("Your choice: ");
        scanf_s(" %d", &choice);
        printf("\r\n");

        switch (choice)
        {
        case 1:
            PushStack(&stack, maxEl);
            break;
        case 2:
            PopStack(&stack);
            break;
        case 3:
            Print(stack.next);
            break;
        case 4:
            printf("\r\nExiting..."); choice = 4;
            break;
        default:
            printf("\r\nWrong choice, try again. \r\n");
        }
    }

    return 0;
}

int PushStack(Position head, int max)
{
    int target = 0;
    target = rand() % (100 - 10 + 1) + 10;
    if (ArrayLength(head) < max)
        AddFirst(head, RandomValue(target));
    else
    {
        AddFirst(head, RandomValue(target));
        DeleteLast(head);
    }

    return 0;
}

int PopStack(Position head)
{
    head->next = head->next->next;
    return 0;
}

int AddFirst(Position head, Position newEl)
{
    newEl->next = head->next;
    head->next = newEl;

    return 0;
}

Position RandomValue(int number)
{
    Position newNode;
    newNode = (Position)malloc(sizeof(Node));
    if (newNode == NULL)
        return NULL;
    newNode->value = number;
    newNode->next = NULL;

    return newNode;
}

void Print(Position p)
{
    while (p != NULL)
    {
        printf("%d \t", p->value);
        p = p->next;
    }
    printf("\r\n\r\n");
}

int ArrayLength(Position head)
{
    int counter = 0;
    while (head->next != NULL)
    {
        counter++;
        head = head->next;
    }
    return counter;
}

void DeleteLast(Position head)
{
    while (head->next->next != NULL)
        head = head->next;
    head->next = NULL;
}