3-add_node_end.c

#include "lists.h"
/**
 * add_node_end - adds a new node at the end of a list_t list
 * @head: double pointer to list_t
 * @str: pointer to the first node in list_t
 * Return: a poitner to the new node or NULL if it failed
 */
list_t *add_node_end(list_t **head, const char *str)
{
	int runner;
	list_t *new_end_node;
	list_t *firstnode;

	new_end_node = malloc(sizeof(list_t));
	runner = 0;
	if (new_end_node)
	{
		new_end_node->str = strdup(str);
		/* task condition */
		if (!new_end_node->str || !str)
		{
			free(new_end_node);
			return (NULL);
		}
		/* go through str to know the lenght */
		/* and assign this to the len variable */
		/* and de-reference to new_end_node */
		while (new_end_node->str[runner])
			runner++;
		/* new_end_node will go fordward till is equal to NULL */
		new_end_node->next = NULL;
		new_end_node->len = runner;
		/* this condition is necesary to avoid core dumped */
		if (!*head)
		{
			*head = new_end_node;
			return (new_end_node);
		}
		/* first node will be equal to the pointer to the */
		/* first element of the linked list */
		firstnode = *head;
		/* I go through the linked list */
		while (firstnode->next)
			firstnode = firstnode->next;
		/* first node looks for next node till finds new_end_node */
		firstnode->next = new_end_node;
		return (new_end_node);
	}
	return (NULL);
}