error LNK2005...

give a little more information.

What do you mean a global function in a class? Do you mean public and/or static? Do you have inclusion guards in your .h files? Some code would help.
The linker error means you have something defined multiple times.

[edit] it says __cdecl, so do you have the implementation of a function in an h file?


Regards,
jflanglois

Instead of:

header.hhvoid pie ( void ){}somesource1.cc#include "header.hh"somesource2.cc#include "header.hh"

Do:

header.hhvoid pie ( void );header.ccvoid pie ( void ){}somesource1.cc#include "header.hh"somesource2.cc#include "header.hh"

MaulingMonkey, thanks, that worked!
thank you :-)

Quote:

Original post by Ilankt MaulingMonkey, thanks, that worked! thank you :-)

Do you understand why it worked?

I think so, it's like having 2 functions that take the same parameters, with the same name, so the linking program cant decide which of both of them to use.
am I right?

Exactly. Including the file header.hh makes your function definition appear in two .cc files which results in two translation units (files generated from your .cc files) containing definitions for that function. The linker then looks for a definition in all translation units, finds two and dies because it doesn't know which to use.

Using a declaration instead of a definition, using « foo( ); », tells the linker what the function looks like, without actually including its definition in the translation unit.

Quote:

Original post by Ilankt I think so, it's like having 2 functions that take the same parameters, with the same name, so the linking program cant decide which of both of them to use. am I right?

Yep. When the C++ file is preprocessed, the whole include file is copied into the C++ file to create a preprocessed file. The file is then compiled and all the symbols which are defined as global in this compilation unit (and this definition is by default - you'll have to change the declaration of your symbol to make them local to the compilation unit) are exported. When you compile 2 C++ file which exports the same symbols, the linker don't know which one he might choose - the linker is not able to know that the code is the same. Therefore it screams.

header files should be used to declare (prototype) symbols, while C++ files should be used to define (implement) them.

Of course, when you'll understand this better, you'll be able to play with it - because, as you may know, there are some syntax manipulation which enable you to define symbols in the header file.

HTH,