Compiling multiple C files having underlying functions from a common file - c

Question

I went through all StackOverflow threads regarding this but could not find one that matched my problem.
I am trying to implement different data structures (implemented in stack.c, queue.c) which get basic functions from another file storage.c. Here are their header files -
storage.h
typedef struct _circular_list
{
int *array, head, tail;
size_t size, count;
} circular_list;
typedef circular_list *clist;
clist Initialize(size_t);
clist WriteAtTail(clist, int);
int RemoveAtHead(clist);
int RemoveAtTail(clist);
clist WriteAtHead(clist, int)
stack.h
#include "storage.h"
#define stack clist
#define push(s, i) WriteAtTail(s, i)
int pop(stack);
int popKey(stack, int);
queue.h
#define queue clist
#define EnQueue(q,i) WriteAtTail(q,i)
#define DeQueue(q) RemoveAtHead(q)
I include them in the main C file
driver.c
#include <stdio.h>
#include "stack.h"
#include "queue.h"
Now if i try to compile them using
gcc -o driver driver.c storage.c stack.c queue.c
I get an error unknown type name 'clist' in queue.h.
If I try to include storage.h in queue.h as well, I get an error that I have multiple declarations for the structure.
How do I go about compiling this?

Answer 1

If you don't include storage.h in stack.h or queue.h you have to include it in your driver.c file before including one of the other files. Otherwise the compiler does not know about the declarations of storage.h.
A better solution is to include storage.h directly in stack.h and queue.h. To avoid getting compiler errors due to multiple declarations you have to change your storage.h like this:
#if !defined(INC_STORAGE_H)
#define INC_STORAGE_H
/* original storage.h contents go here */
#endif /* INC_STORAGE_H */
Or simply write #pragma once at the beginning of the storage.h if your compiler supports it. (If you're writing a library for other people to use I recommend the first solution)