Beginner's Problem With First Funtion

[Ohrange]

Hi, I'm working through the You Can Do It! book by Francis Glassborow and am stuck on the chapter that introduces functions. Can anyone tell me why this won't build?

#include <iostream>
#include "playpen.h"
#include "drawing_functions.h"

using namespace fgw;
using namespace std;

int main(){
 playpen paper;
 paper.scale(3);
 draw_a_cross(paper,-4,0,9,0,-4,9,black);
 paper.display();
 cout << "press return to end";
 cin.get();
 }

The drawing functions header I made and it contains:

#ifdef DRAWING_FUNCTIONS_H
#define DRAWING_FUNCTIONS_H

#include "playpen.h"

void draw_a_cross(fgw::playpen &,
 int left_of_cross_piece_x, int left_of_cross_piece_y,
 int width_of_cross,
 int bottom_of_cross_piece_x, int bottom_of_cross_piece_y,
 int height_of_cross,
 fgw::hue);

#endif

The playpen header makes all the paper and fgw stuff work fine. The IDE I'm using is Quincy. These are the errors I'm getting:
http://www.picvault.info/images/5370...ildproblem.bmp

Any help would be greatly appreciated.

[brewbuck]

playpen.h must include a prototype for the draw_a_cross function

[Daved]

It looks like playpen.h does include the prototype for draw_a_cross. I think the error is because drawing_functions.cpp does not #include "drawing_functions.h".

[maxhavoc]

I'm not sure if this is the cause of the problem, but...

#ifdef DRAWING_FUNCTIONS_H
#define DRAWING_FUNCTIONS_H

Should be...

#ifndef DRAWING_FUNCTIONS_H
#define DRAWING_FUNCTIONS_H

Otherwise, DRAWING_FUNCTIONS_H is never defined, which might cause the function prototype never to be interpreted by the compiler.

[Ohrange]

Thanx maxhavoc that little "n" made all the difference! Thanks also to the others who replied.