Multiple Definition Compile Error

[mikejfe]

Hi all. I am having multiple definition compiling errors. I included the #ifndef, #define, #endif lines in my header files. I've seen a post on here suggesting using extern. That didn't work for me either. This is a snippet from my header file.

#ifndef ListVars_h
#define ListVars_h

extern int bonesDL = 3;
extern int marrowDL = 4;

#endif

If I include ListVars.h into multiple .cpp files and compile, I get the error. Any ideas? I'm using Dev-C++ with Windows XP.

Thank you!
-Michael

[Banfa]

You can not initialise in a declaration so you need

extern int bonesDL;
extern int marrowDL;
 

in your header and

int bonesDL = 3;
int marrowDL = 4;
 

in a source file somewhere

[mikejfe]

Hmm. Well I tried a few different things and I still get the multiple definition error. Maybe I didn't quite understand your response (sorry). The header file now reads:

#ifndef ListVars_h
#define ListVars_h
 
extern int bonesDL;
 
#endif
 

One thing I tried was adding a new function:

#include "ListVars.h"
 
void initVars()
{
int bonesDL=3;
}
 

And then I tried:

#include "ListVars.h"
 
void initVars()
{
bonesDL=3;
}
 

And finally I tried (as a last effort):

#include "ListVars.h"
 
int bonesDL=3;
void initVars()
{
}
 

I also tried all of these variations without using extern in the header file.

Thanks for your help,
-Michael

[horace1]

the declaration in your header files looks OK:

#ifndef ListVars_h
#define ListVars_h
 
extern int bonesDL;
 
#endif
 

it must be defined in only ONE of your .c files

int bonesDL=3;
 

if you are getting multiple definitions of this identifier you must have it defined in more than one c file

in this version

#include "ListVars.h"
 
void initVars()
{
int bonesDL=3;
}
 

you define it as a local variable, remove the 'int'

[mikejfe]

It finally compiled! I'm pretty new to writing C++ programs that are more advanced than "Hello World." My grad professor stuck me on a program that requires knowledge of openGL and C++ ... and I've been struggling. Thank you so much for your help!