7-insert_dnodeint.c

#include "lists.h"
/**
 * insert_dnodeint_at_index - inserts a new node at a given position.
 * @h: pointer to the head of the list
 * @idx: index of the list where the new node should be added
 * @n: data of the new node
 * Return: the address of the new node, or NULL if it failed
 */
dlistint_t *insert_dnodeint_at_index(dlistint_t **h, unsigned int idx, int n)
{
	unsigned int counter = 0;
	dlistint_t *new_node = NULL, *tmp = NULL;

	if (h == NULL)
		return (NULL);
	if (idx == 0)
		return (add_dnodeint(h, n));
	tmp = *h;
	while (tmp != NULL)
	{
		if (counter == idx - 1)
		{
			if (tmp->next == NULL)
				return (add_dnodeint_end(h, n));
			new_node = malloc(sizeof(dlistint_t));
			if (new_node == NULL)
				return (NULL);
			new_node->n = n;
			new_node->next = tmp->next;
			new_node->prev = tmp;
			tmp->next->prev = new_node;
			tmp->next = new_node;
			return (new_node);
		}
		tmp = tmp->next;
		counter++;
	}
	return (NULL);
}