Field has incomplete type

[cguy]

This is the code:

struct directory;
typedef struct directory directory_t;

typedef struct file
{
char name[256];
unsigned long size;
date_t created;
date_t modified;
directory_t parent; <---------- This line is troublesome
}file_t;


struct directory
{
char name;
struct directory *parent;
date_t created;
date_t modified;
};

and this is the compilation error:

error: field 'parent' has incomplete type

But I declared the second structure's prototype and then declared a type definition.

Why do I still get an error?

[worksofcraft]

This is the code:

struct directory;
typedef struct directory directory_t;

typedef struct file
{
char name[256];
unsigned long size;
date_t created;
date_t modified;
directory_t parent; <---------- This line is troublesome
}file_t;


struct directory
{
char name;
struct directory *parent;
date_t created;
date_t modified;
};

and this is the compilation error:

error: field 'parent' has incomplete type

But I declared the second structure's prototype and then declared a type definition.

Why do I still get an error?

That is correct.
The declaration of struct directory is AFTER the definition of "parent"... so when the compiler is trying to work out the size of your struct file... it doesn't yet know how big the directory structure is.

You can either make it so the declaration of directory comes BEFORE file or you can declare a parent as a POINTER which has the same size no matter what it points to :)

p.s. If I understand what you are trying to do... then you simply have to put a * in front of parent on that line!