Thread: Linkage error

Hello,

I have used C in the past. but have gotten EXTREMELY rusty at it. I currently have four files in my directory (ex.c, ex.h, menu.c, and menu.h).

menu.h is this:

Code:

#ifndef MENU_H
#define MENU_H

#include <stdio.h>

void print_header(void);
int get_choice(void);

#endif

menu.c is this:

Code:

#include "menu.h"

void print_header(void) {
    printf("--- Chapter 1 Examples ---\n");
}

ex.h is this:

Code:

#include <stdio.h>

void ex_1(void);

and ex.c is this:

Code:

#include "ex.h"
#include "menu.h"

int main() {
    print_header();
    return 0;
}

Currently, I am trying to run print_header in ex.c to make sure everything works but I am getting a linkage error.

Code:

ex.c:(.text+0x9): undefined reference to `print_header' 
collect2: error: ld returned 1 exit status

Can someone refresh why this is happening and how to fix it? Thank you