Thread: Linker Error

Hey,

I've got the usual Visual C++ MFC program going. It's got a main dialog, with two (not-main?) dialogs that are called with DoModal().

The thing is that those two dialogs need the same files, which have the same functions and classes.

Here's an example of what I mean

MyClass.cpp

Code:

#include <windows.h>

class MyClass
{
	public:
	int a;
	int b;
	char c;
};

Functions.cpp

Code:

void doSomething()
{
	//code to do something in here
}

int DoSomethingAsWell ( int i )
{
	//Do something here
}

And then the header for both of the *.cpp files that apply to the DoModal dialogs looks like this:

Code:

#include "MyClass.cpp"
#include "Functions.cpp"

MyClass mc;

This code results in a bunch of linker errors (LNK2005, and LNK1169 for the last error). It's telling me the functions already exist in the other dialogs .obj file, however, if I don't include the file in the *.cpp file, it says that the functions/classes don't exist. So, it's either it doesn't exist, or it's already been defined!


Here's the actual link error:

Originally Posted by Micro$oft

1>MacroCfgDlg.obj : error LNK2005: "class ATL::CStringT<wchar_t,class StrTraitMFC<wchar_t,class ATL::ChTraitsCRT<wchar_t> > > __cdecl to_vkey(int)" (?to_vkey@@YA?AV?$CStringT@_WV?$StrTraitMFC@_WV?$C hTraitsCRT@_W@ATL@@@@@ATL@@H@Z) already defined in AntiRecoilCfgDlg.obj
1>MacroCfgDlg.obj : error LNK2005: "unsigned long __stdcall getkey(void *)" (?getkey@@YGKPAX@Z) already defined in AntiRecoilCfgDlg.obj
1>MacroCfgDlg.obj : error LNK2005: "void __cdecl set_key(struct HWND__ *,int &)" (?set_key@@YAXPAUHWND__@@AAH@Z) already defined in AntiRecoilCfgDlg.obj
1>E:\Programming\Visual Studio 2008\Quick Keys\Debug\Quick Keys.exe : fatal error LNK1169: one or more multiply defined symbols found

If you guies need the actual source code I'd be happy to post that as well.

Thanks in advance,

Guitarist809

#include "MyClass.cpp"
#include "Functions.cpp"
DO NOT do this!!!
Each including file makes a copy of the code, and if you do it more than once, you end up with "multiply declared" symbols.

You can include .h files in other .h files
Looks like you need to include MyClass.h and Functions.h here.

Implementation files (that's the .cpp files) go into the "project->settings Add source files..."