Undefined Reference to function?

Our assignment is to write a program that tests our teacher's code. He has written 4 files for us to "test". However, when I try and compile it, it cant find only 1 of his functions, but the rest it does fine on. Ill attach the relevent part in my code, and how he has his code set up.

Code:

#include <stdio.h>
#include <stdlib.h>
#include "ssm.h"
#define	DEBUG	1
int l;
l = eat_comment(argv[2]);

The only difference between the rest of the functions, and "eat_comment()" is that it is in the same file as read_route, and ssm.h doesnt mention eat_comment. Is there a way to get it to recognize eat_comment without changing his code?

Code:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "ssm.h"

#define VERSION "0.5"

static int eat_comment(FILE *fp);  // eats commnts and white space
static int line;                   // line in file currently being read.

// int read_route(const char *file, const Route *route) {
int read_route(const char *file, Route *route) {
.
.
.
}

// eat_comment() eats white space and commnets, incrementiong
// the line counter as it goes. If one of the fscanfs above
// eats a '\n' between parameters, the line count will be off.
// Perhaps the "line" count is not such a good idea here after all
// That can be fixed if above '\n' is not accepted as a delimiter
// between parameters. hummm....
static int eat_comment(FILE *fp) {
.
.
.
}

And the ssm.h part where it includes read_route and write_route :

Code:

defines a bunch of variables/structs...
int read_route(const char *file, Route *route);
int write_route(const char *file, const Route *route);

What you can do is put a prototype for the function somewhere in your code before the "int main()" line. Like this:

Code:

static int eat_comment(FILE *fp);

But you also have a problem with your call:

Code:

l = eat_comment(argv[2]);

You are passing a pointer to char, but eat_comment() takes a pointer to FILE. Once you add the function prototype, the compiler will point this out to you.

>int main()
Make that:

Code:

int main(void)

Absentmindedly thought I was reading the C++ board.

When I just add the prototype up top, it just says its used, but never defined. And yes, ill have to cast the arg someway else.

>When I just add the prototype up top, it just says its used, but never defined.

>int l;
>l = eat_comment(argv[2]);
You do realize this code goes in your main program?

When I add the prototype to the header file, and remove the static keyword, it works out.

>int main()
Make that:

Code:

int main(void)

Absentmindedly thought I was reading the C++ board.

() only means "no information available about function arguments" in a function prototype (in C). For a function declaration, it means the same thing as (void). So

Code:

int main() {
    return 0;
}

is the same as

Code:

int main(void) {
    return 0;
}