c - enum declaration in header file -

i have files a.c , b.c , b.h . in a.c there

enum cmd{     first,     second,     third, }; 

and later in file there is

bool function(...){ //... enum cmd data_type = first; //... } 

in file b.c need use

if (data_type == first){...} 

i tried include in b.h this:

extern enum cmd data_type; 

and included #include "b.h" in a.c , b.c . files in propper folders of project. no cigar :( line in b.c gives this:

20: identifier "from_sms" undefined 70: incomplete type not allowed 

how make work. a.c file writen else , i'm modifiing code b.c . original code mess , wan fidlle less possible :) architecture ie stm32 , i'm using uvision 3 ide.

thank you

an enum type, should put in in .h.

extern keyword variables.

edit: sorry, had badly read code.

here problem try use enum without having defined. think when compiler compiles something, takes every .c file separately, , "copies" content of include c file.

so here have b.c includes b.h since declaration of type in a.c, compiler has no way of knowing it, hence throwing error when trying compile b.c.

to solve it, declare type @ top of b.h , include in both files, or create "myenum.h" file include in .h / .c files require it.