C #include and constants problem

I have these two files, functions.c and constants.h.

functions.c has this line:

#include "constants.h"

However, when I try to compile functions.c, functions.c functions can't find these constants from constants.c. These are const type constants. I know it's a very noobish problem, but I don't know the solution.

EDIT: Files content (some of them):

functions.c:

#include <string.h>
#include "Directivas.h"
...
int hayDirectivaInclude(char* buffer) {
    if (strncmp(include, buffer, longInclude) == 0)
        return 1;
    else
        return 0;
}

constants.h:

const char include[10] = { '#', 'i', 'n', 'c', 'l', 'u', 'd', 'e', ' ', 0 };
const int longInclude = 9;

Your constants.h must contain extern references to the constants.

For example, suppose you had: const char* COOL_STRING = "Erandros is cool." in constants.c. In order for functions.c to know about this string, you must inform it of its existence by writing extern char* COOL_STRING; somewhere, such as in constants.h

Are the constants declared in constants.h? You should at least declare them there, or else the compiler won't know they exist when processing functions.c.

see suppose you have declared some function in constants.h and its defination are in constants.c then when you are compiling function.c " just by including constants.h will not have include defination of those function . so it will give error...you need to compile both .c file wit together.