Question

I am trying to make the s_cord_print function visible in the cord_s.c file only. Currently the function is visible/runnable in main.c even when it is declared static.

How do I make the s_cord_print function private to cord_s.c?

Thanks!

s_cord.c

typedef struct s_cord{
  int x;
  int y;
  struct s_cord (*print)();
} s_cord;

void* VOID_THIS;
#define $(EL) VOID_THIS=⪙EL

static s_cord s_cord_print(){
  struct s_cord *THIS;
  THIS = VOID_THIS;
  printf("(%d,%d)\n",THIS->x,THIS->y);
  return *THIS;
}

const s_cord s_cord_default = {1,2,s_cord_print};

main.c

#include <stdio.h>
#include <stdlib.h>

#include "s_cord.c"

int main(){
  s_cord mycord = s_cord_default;
  mycord.x = 2;
  mycord.y = 3;
  $(mycord).print().print();
  //static didn't seem to hide the function
  s_cord_print();
  return 0;
}

~

Answer 1

The problem is:

#include "s_cord.c"

You should remove that. Instead, create a s_cord.h file that contains only declarations, such as:

typedef struct s_cord{
  int x;
  int y;
  struct s_cord (*print)();
} s_cord;

and put:

#include "s_cord.h"

in main.c and s_cord.c. You also need an extern declaration for s_cord_default. So the complete code is:

s_cord.c:

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

void* VOID_THIS;

static s_cord s_cord_print(){
  struct s_cord *THIS;
  THIS = VOID_THIS;
  printf("(%d,%d)\n",THIS->x,THIS->y);
  return *THIS;
}

const s_cord s_cord_default = {1,2,s_cord_print};

s_cord.h:

typedef struct s_cord{
  int x;
  int y;
  struct s_cord (*print)();
} s_cord;

#define $(EL) VOID_THIS=⪙EL

extern const s_cord s_cord_default;
extern void *VOID_THIS;

main.c:

#include <stdio.h>
#include <stdlib.h>

#include "s_cord.h"

int main(){
  s_cord mycord = s_cord_default;
  mycord.x = 2;
  mycord.y = 3;
  $(mycord).print().print();
  return 0;
}

You’ll now get a error if you try to call s_cord_print() from main, as expected.

EDIT: I forgot to move the $(EL) definition, and it needed an extern for VOID_THIS.

EDIT 2: The correct compilation command is:

gcc s_cord.c main.c -o main