Thread: Struct inside a Struct inside a Struct?!?

i seem to be having problems with some code.. and to be honest i can't figure out why... i won't post my code but i'll post something similar...

Code:

// One.h

#ifndef ONE_H
#define ONE_H

#include "Two.h"

struct One
{
  int stuff;
  One *next;
  Two *list;
}

#endif

Code:

// Two.h

#ifndef TWO_H
#define TWO_H

#include "One.h"

struct Two
{
  unsigned int otherStuff;
  Two *next;
  One *back; // THis is where the error occurs.
}

#endif

What i do is make a pointer to a One struct, however the error pops up at where i designated.. it basically won't let me define a [b]One[b] inside a Two struct.. why can't i make a struct point to another struct and that struct point back to the first type of struct... (making a linked list of linked lists)

You might need to typedef the structs, or at least refer to them as structs.

Code:

struct One
{
  int stuff;
  struct One *next;
  struct Two *list;
}

Code:

struct Two
{
  unsigned int otherStuff;
  struct Two *next;
  struct One *back; 
}

Other suggestions are to not put them in different header files, since they are dependent on each other. I don't know if you can declare variables as externs in C++ or not, but that could also help.

Greetings,

C++ is all about classes! Besides, structs are classes in C++, the only difference (apperently) is that in struct's the members default to public where in classes it defaults to private.

Ah, yes. It's been a while since I've programmed anything with classes, so I kinda forgot what I was doing on for a second. Anyway, I don't know exactly what the error message says, but I think Brighteyes is on the right track with having to somehow delcare the struct as a known variable beforehand.

As an aside: Even though something may not be necessary, my experience tells me that programs sometimes work better if it's done anyway.

ah quick replies.. nice.. i'll try some of ur guys suggestions and see if i can get it to work...

yeah i tried to put both structs in same file but since i never used forward declarations before it makes it kinda hard :P .. i gotta remember forward decs'... could be useful... yeah there is externs in c++ too.. might give that a whirl as well..

i've never seen any code written where u refer to the datatypes by structs struct One *next; but if that works that could be pretty cool too..



i'lll get back to ya'll if i run into more problems... thnx for the help