Thread: Defining a struct with 2-way pointers

Hi there.

I want to define a struct which has 2 pointers which point to diferent "things". I wanna have a linked list where each node is the head of a separate linked list. something like an excel sheet where you can dynamically resize the number of rows and columns, but with the exception that each "row" can have diferent number of columns

Code:

 [floor1]->room101->NULL
    v
 [floor2]->NULL
    v
 [floor3]->room301->room302->room303->NULL
    v
 [floor4]->room401->room402->NULL
    v
  NULL

i tried something like this but it doesn't work...

Code:

struct node1
{
  int roomnumber;
  struct node1 *nextroom;
}

typedef struct node2
{
  int floornumber;
  struct node1 room;
  struct node2 *nextfloor;
} floor;

I don't see why it doesn't work. Maybe you are not using it correctly? Post also your test code or the error you get.

Note: Just want to point out that in C++ this could be done really easy, since the structures desired would be ready for you

it doesn't even compile :-(

http://www.imagesforme.com/out.php/i681024_error.PNG

stupid semicolon

but tell me, I have other problems. how do I acess the field "roomnumber"?

Code:

floor *new2 = malloc(sizeof(floor));
	new2->floornumber = 2;
	new2->nextfloor = NULL;
	new2->room->roomnumber = 201;
	new2->room.roomnumber = 201;
	new2.room->roomnumber = 201;

the red are my suggestions. I must admit, I am really flaky when it comes to structures in structures which both have pointers

Why do you need struct node2 *nextfloor as a member of struct node2 because IMO it'll always point to NULL?

Originally Posted by itCbitC

Why do you need struct node2 *nextfloor as a member of struct node2 because IMO it'll always point to NULL?

It will point to the next node, since it is a linked list?

thanks guys. i get it now.