compilation - Compiling multiple C files in a program

Question

I have the following two files:

file1.c

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

file2.c

void foo(){

 }

Can I compile and link the two files together so the file1.c will recognize the foo function without adding extern?

Updated the prototype.

gcc file1.c file2.c throws: warning: implicit declaration of function foo.

Answer 1

The correct way is as follows:

file1.c

#include <stdio.h>
#include "file2.h"

int main(void){
    printf("%s:%s:%d 
", __FILE__, __FUNCTION__, __LINE__);
    foo();
    return 0;
}

file2.h

void foo(void);

file2.c

#include <stdio.h>
#include "file2.h"

void foo(void) {
    printf("%s:%s:%d 
", __FILE__, __func__, __LINE__);
    return;
}

output

$
$ gcc file1.c file2.c -o file -Wall
$
$ ./file 
file1.c:main:6 
file2.c:foo:6 
$