Implement add_dnodeint_end function to insert a new node at the end

Created a new node and linked it appropriately
Handled memory allocation failure gracefully
Handled both empty and non-empty lists
Updated the prev and next pointers accordingly
Added proper documentation and comments

Author: nwhator

0x17-doubly_linked_lists/3-add_dnodeint_end.c

@@ -0,0 +1,38 @@
+#include "lists.h"
+
+/**
+ * add_dnodeint_end - Adds a new node at the end of a dlistint_t list.
+ * @head: Double pointer to the head of the list.
+ * @n: Value to be stored in the new node.
+ *
+ * Return: Address of the new element, or NULL if it failed.
+ */
+
+dlistint_t *add_dnodeint_end(dlistint_t **head, const int n)
+{
+	dlistint_t *new, *temp;
+
+	new = malloc(sizeof(dlistint_t));
+	if (!new)
+	{
+		return (NULL);
+	}
+	new->n = n;
+	new->next = NULL;
+	temp = *head;
+	/* Empty list, new node becomes the head */
+	if (!temp)
+	{
+		new->prev = NULL;
+		*head = new;
+		return (new);
+	}
+	while (temp->next)
+	{
+		temp = temp->next;
+	}
+	/* Insert new node at the end of the list */
+	temp->next = new;
+	new->prev = temp;
+	return (new);
+}

0x17-doubly_linked_lists/3-main.c

@@ -0,0 +1,26 @@
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+#include "lists.h"
+
+/**
+ * main - check the code
+ *
+ * Return: Always EXIT_SUCCESS.
+ */
+int main(void)
+{
+    dlistint_t *head;
+
+    head = NULL;
+    add_dnodeint_end(&head, 0);
+    add_dnodeint_end(&head, 1);
+    add_dnodeint_end(&head, 2);
+    add_dnodeint_end(&head, 3);
+    add_dnodeint_end(&head, 4);
+    add_dnodeint_end(&head, 98);
+    add_dnodeint_end(&head, 402);
+    add_dnodeint_end(&head, 1024);
+    print_dlistint(head);
+    return (EXIT_SUCCESS);
+}