[CheckersW]

The code:

typedef int item;
typedef node* Node;

typedef struct _node {
   item value;
   Node next;
} node;

typedef struct _stack  {
   Node first;
} stack;

The issue I'm having is that my struct "node" and my typedef "Node" are sort of interdependent, so if I define "node" first, the compiler freaks out (DynamicStack.c:13: error: expected specifier-qualifier-list before 'Node'), but if I define "Node" first, the compiler has a different freakout.

How should I order these definitions?

[baavgai]

Ack, don't typedef pointers! How the hell do you know it's a pointer then?

typedef int item;

typedef struct _node {
	item value;
	struct _node *next;
} node;

typedef struct {
	node *first;
} stack;

If you must, well, you still have to use the full syntax on the next. You then do the second typedef after it's declared e.g.

typedef struct _node {
	item value;
	struct _node *next;
} node;

typedef node *Node;

[turboscrew]

Compiler needs to be tols about the existence of a symbol before it can be used.

You can't typedef a new type until all parts of the "old" type are at least declared.

That's why, if you define a self-referencing structure, you need to use the structure tag. The typedef is not defined yet when you are defining the self-referring field. The tag acts as a declaration.

like:

typedef struct my_struct
{
  struct my_struct * self_reference; /* my_type is not yet known */
} my_type;

[CheckersW]

Excellent, thanks all.

baavgai, on 26 May 2012 - 04:37 AM, said:

Ack, don't typedef pointers! How the hell do you know it's a pointer then?

And yeah... I'm not a fan of typedeffing pointers, but it's part of my assignment and my lecturer requires that it be done like that (automated testing). Unfortunate, I know...

[Skydiver]

baavgai, on 26 May 2012 - 03:37 AM, said:

Ack, don't typedef pointers! How the hell do you know it's a pointer then?

This is where Hungarian notation pays huge dividends...

typedef struct _node
{
    // Other node fields here

    struct _node * m_pnode;    // 'm_pnode' translates to member pointer to node
} NODE;

typedef NODE * PNODE;          // 'PNode' translates to pointer to node

PNODE g_pnodeHead = 0;         // 'g_pnodeHead' translates to global pointer to node called 'Head'.

PNODE PnodeFindNth(int n)      // function returns a pointer to a node that was found to be the n-th element.

Personally, though, I agree with baavgai that one shouldn't typedef pointers. In Windows programming, though PCWSTR is so much easier to type and understand as a pointer to a constant wide character string as opposed to 'const wchar_t *' or some such. :-)