C - Headers including each other

Question

I have a file game.h which has this declaration

typedef struct Enemy {
  ...
}Enemy;

And a function

void moveEnemy(Level* l, Enemy* enemy){
  ...
}

Level is declared on levels.h, so in game.h I have:

#include "levels.h"

Everything was perfect, until I had to use Enemy in levels.h.

So, in levels.h I added:

#include "game.h"

And now I get a compilation error:

game.h:34:2: error: unknown type name ‘Level’
  Level* level;
  ^

I have include guards on both .h

I don't know why I can't have on file including another.

What can I do?

I don't understand the question, is `moveEnemy()` defined in the header file? If it is, it should not! — Iharob Al Asimi, Jan 12 '16 at 14:25
No, see the answer. But YES never put functions in header files. Header files are meant ot include function prototypes, constants and declarations, definitions of structures or user defined data types, etc. Not function definitions, those belong to *.c* files. — Iharob Al Asimi, Jan 12 '16 at 14:27
Use 'extern'. http://stackoverflow.com/questions/1433204/how-do-i-use-extern-to-share-variables-between-source-files-in-c — user1643650, Jan 12 '16 at 14:28
Have you tried this http://stackoverflow.com/questions/3246803/why-use-ifndef-class-h-and-define-class-h-in-h-file-but-not-in-cpp ? — ganchito55, Jan 12 '16 at 14:39

score 1 · Accepted Answer · answered Jan 12 '16 at 14:26

1

Just add a forward declaration, like this in game.h before the function,

typedef struct Level Level;

since it's just a pointer to Level this will do it.

answered Jan 12 '16 at 14:26

Iharob Al Asimi

it solved that problem, but created another. Now when I use the struct Level, as in "lev->map", I'm getting the error: derreferencing pointer to incomplete type. I was not getting this error before – Aleksandrus Jan 12 '16 at 14:36
Move the functions to the *.c* files, and then include *level.h* there. – Iharob Al Asimi Jan 12 '16 at 14:37
one question. the includes should be on the .c, .h or both? – Aleksandrus Jan 12 '16 at 14:40
Maybe on both as per your setup. – Iharob Al Asimi Jan 12 '16 at 14:41

1 Answers1