Thread: Linker Errors

--> x already defined in y.obj

I've just about had it with this problem. How the hell do I fix this?

I have a main.h file with all function defs, globals, macros etc.

Then I have many .cpp files which include main.h.

I took this type of file layout from CDX's code, and problem is, their code links, mine doesn't.

There's virtually no difference between their code, and mine, in terms of file layout.

I'm using VS .NET

Even with include guards I get the errors.

Let's say my main.h looks like this:

Code:

#include <windows.h>
#include <stdio.h>
#include <vector>

using std::vector;

//Define macros here
#define PI  3.141592654
//End Define macros

//Globals here
#ifdef MAIN_CPP
   #define DECLARE
#else
   #define DECLARE extern
#endif

DECLARE int globalVariable;
DECLARE char globalString;
//End Globals

//All function prototyes
int WINAPI WinMain(...);
LRESULT CALLBACK WndProc(...);

int function();
void function_2();
//End Function Prototypes

Now, in main.cpp, i'll have something like this:

Code:

#define MAIN_CPP
#include "main.h"

int WINAPI WinMain(...)
{
}

LRESULT CALLBACK WndProc(...)
{
}

Then I have about six other .cpp files which include main.h


One other thing:
If project A was originally built with VS 6, and project B is originally built with VS .NET, would there be any difference between the two projects if the VS 6 project was converted to a VS .NET project?