Question

I want use a typedef struct that isn’t already defined, but it is later.
Is there anything like a struct prototype?

file container.h

// i would place a sort of struct prototype here
typedef struct 
{
 TheType * the_type;
} Container;

file thetype.h

typedef struct {......} TheType;

file main.c

#include "container.h"
#include "thetype.h"
...

Answer 1

Replace this line:

// i would place a sort of struct prototype here

with these lines:

struct TheType;
typedef struct TheType TheType;

Since you need the type TheType to be defined before type Container is defined, you have to use forward declaration of type TheType – and to do so you also need forward declaration of struct TheType.

Then you will not define typedef TheType like this:

typedef struct {......} TheType;

but you will define struct TheType:

struct {......};