[wellylug] C++ Programing Problem

[Stephen Judd]

On Sun, 2003-09-07 at 13:59, Jethro Carr wrote:
> I think it's a simple solution, but I don't know it....:(

1. Make sure you avoid multiple inclusion

#ifndef JGAME
#define JGAME

#include jgame2d/jgame2d.h

#endif

But I think your real problem is this:

2. Ensure globals in header files are defined with extern, thus:

(in jgame2d.h)

extern int keyboard_state; // this is now simply a declaration

Otherwise, the jolly old compiler sees this:

(in jgame2d.h)
int keyboard_state; // declaring AND defining

as the first definition, and will barf on the "second" one in your .cpp
file.

See http://website.lineone.net/~michael.s.grant/faq.html#multiple-def

HTH

Stephen