// The following code is meant to ask the user to continuously enter **char**
// inputs, to be inserted at the head of a linked list until CTRL+D is pressed.
//
// Inputs that are not digits (between 0-9 inclusive) result in "Input
// '[character]' is not a digit!" being printed, and not adding to the linked
// list. This means that only digit inputs can be added to the linked list.
//
// The list is printed after CTRL+D is pressed, which should result in printing
// all digits scanned in, in reverse order.
//
// However, there are a number of issues found in the code that you need to fix
// Good luck!

#include <stdio.h>
#include <stdlib.h>

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

struct node *prepend_list(struct node *list, int data);
void print_list(struct node *list);

int main(void) {
    struct node *list = NULL;

    char input;
    printf("Enter digits:\n");
    int success = scanf(" %c", &input);
    while (success == 0) {
        if (input <= '0' && input > '9') {
            printf("Input '%c' is not a digit!\n", input);
        } else {
            list = prepend_list(list, input);
        }

        success = scanf(" %c", input);
    }

    print_list(list);
    return 0;
}

// Prints all elements in the given `list`
void print_list(struct node *list) {
    struct node *curr = list;
    while (curr != NULL) {
        printf("%d ", curr->data);
        curr = curr->next;
    }
    printf("\n");
}

// Creates and adds a new node with given `data` to the head of a given `list`.
// Returns a pointer to this new head.
struct node *prepend_list(struct node *list, int data) {
    struct node *new = malloc(sizeof(struct node));
    new->data = data;
    new->next = NULL;

    return new;
}