C Program to Reverse a Stack without using Recursion

/*
 * C Program to Reverse a Stack without using Recursion
 */
#include <stdio.h>
#include <stdlib.h>

struct node
{
    int a;
    struct node *next;
};

void generate(struct node **);
void display(struct node *);
void stack_reverse(struct node **);
void delete(struct node **);

int main()
{
    struct node *head = NULL;

    generate(&head);
    printf("\nThe sequence of contents in stack\n");
    display(head);
    printf("\nInversing the contents of the stack\n");
    stack_reverse(&head);
    printf("\nThe contents in stack after reversal\n");
    display(head);
    delete(&head);
    return 0;
}

void stack_reverse(struct node **head)
{
    struct node *temp, *prev;

    if (*head == NULL)
    {
        printf("Stack does not exist\n");
    }
    else if ((*head)->next == NULL)
    {
        printf("Single node stack reversal brings no difference\n");
    }
    else if ((*head)->next->next == NULL)
    {
        (*head)->next->next = *head;
        *head = (*head)->next;
        (*head)->next->next = NULL;
    }
    else
    {
        prev = *head;
        temp = (*head)->next;
        *head = (*head)->next->next;
        prev->next = NULL;
        while ((*head)->next != NULL)
        {
            temp->next = prev;
            prev = temp;
            temp = *head;
            *head = (*head)->next;
        }
        temp->next = prev;
        (*head)->next = temp;
    }
}

void display(struct node *head)
{
    if (head != NULL)
    {
        printf("%d  ", head->a);
        display(head->next);
    }
}

void generate(struct node **head)
{
    int num, i;
    struct node *temp;

    printf("Enter length of list: ");
    scanf("%d", &num);
    for (i = num; i > 0; i--)
    {
        temp = (struct node *)malloc(sizeof(struct node));
        temp->a = i;
        if (*head == NULL)
        {
            *head = temp;
            (*head)->next = NULL;
        }
        else
        {
            temp->next = *head;
            *head = temp;
        }
    }
}

void delete(struct node **head)
{
    struct node *temp;
    while (*head != NULL)
    {
        temp = *head;
        *head = (*head)->next;
        free(temp);
    }
}

OUTPUT

Enter length of list: 8

The sequence of contents in stack
1  2  3  4  5  6  7  8
Inversing the contents of the stack

The contents in stack after reversal
8  7  6  5  4  3  2  1