Why include guards gives no effect for me? Am I missing something?

Question

MainGame.h

#ifndef MainGame_h
#define MainGame_h

#include <string>
#include <sstream>
#include "Horde3D.h"

//definitions

#endif MainGame_h

MainGame.cpp

#include <math.h>
#include <iomanip>
#include "Horde3DUtils.h"
#include "MainGame.h"
#include "GameConfig.h" //<--

//code

main.cpp

#include <iostream>
#include <cstdlib>
#include <cstring>
#include <cstdio>

#include "glfw.h"
#include "MainGame.h"
#include "GameConfig.h" //<--

//code

GameConfig.h

#ifndef GameConfig_h
#define GameConfig_h

#include <string>
#include <sstream>

#define MAX_PATH 260

class GameConfig
{
    static std::string ExtractStartupPath(char *full_app_path)
    {
        const std::string s(full_app_path);

        if(s.find( "/" ) != std::string::npos)
            return s.substr( 0, s.rfind( "/" )) + "/";
        else if(s.find( "\\" ) != std::string::npos )
            return s.substr( 0, s.rfind( "\\" )) + "\\";
        else
            return "";
    }

public:
    static bool IsFullScreen;
    static int StatMode;
    static int FreezeMode;
    static bool DebugViewMode;
    static bool WireframeMode;
    static char *GameTitle;
    static int WindowWidth, WindowHeight;
    static char StartupPath[MAX_PATH];
    static char ContentPath[MAX_PATH];

    static void Initialize(char *startup_path)
    {
        GameTitle = "TestGame\0";

        std::string startup_dir = ExtractStartupPath(startup_path);
        memcpy(StartupPath, startup_dir.c_str(), startup_dir.length() * sizeof(char));

        std::string path(StartupPath);
        path.erase(path.find_last_of('\\'), std::string::npos);
        path.append("\\Content");
        memcpy(ContentPath, path.c_str(), path.length() * sizeof(char));
    }
};

int GameConfig::StatMode = 0;
int GameConfig::FreezeMode = 0;
bool GameConfig::DebugViewMode = false;
bool GameConfig::WireframeMode = false;
bool GameConfig::IsFullScreen = false;
int GameConfig::WindowWidth = 800;
int GameConfig::WindowHeight = 600;
char GameConfig::StartupPath[MAX_PATH] = { 0 };
char GameConfig::ContentPath[MAX_PATH] = { 0 };
char *GameConfig::GameTitle = "TestGame\0";

#endif GameConfig_h

When compiling it I getting linker errors...

main.obj : error LNK2005: "public: static int GameConfig::StatMode" (?StatMode@GameConfig@@2HA) is already define in в MainGame.obj

But I don't understand why... There are only two includes of GameConfig - one in MainGame.cpp and second in main.cpp. Those should never cross. And even if they crossed, what #ifndef GameConfig_h, #define GameConfig_h and #endif GameConfig then for?

I use VC++ 2010 Express Edition

Answer 1

You need to move initialisation of the statics to GameConfig.cpp.

Each source file which includes GameConfig.h is picking up a their own copy of these variables at present.