Re: Linker Error

From:

Abhishek Padmanabh <abhishek.padmanabh@gmail.com>

Newsgroups:

comp.lang.c++

Date:

Mon, 3 Mar 2008 08:51:20 -0800 (PST)

Message-ID:

<2447e773-6ee3-4233-a88a-189249da39f1@s19g2000prg.googlegroups.com>

On Mar 3, 9:43 pm, siddhu <siddharth....@gmail.com> wrote:

Dear Experts,

I am getting a linker error in VC7.

I have written a singleton

//SysInfoFileManager.h

namespace SysInfo
{
        class SysInfoFileManager
        {
                SysInfoFileManager(){}
                SysInfoFileManager(const SysInfoFileManage=

r&);

~SysInfoFileManager(){}
SysInfoFileManager& operator=(const SysI=

nfoFileManager&);

                static SysInfoFileManager* _pinstance;
        public:
                static SysInfoFileManager* instance();
                //void trim(std::string& str);
        };

}

SysInfo::SysInfoFileManager* SysInfo::SysInfoFileManager::_pinstance =
0;

//SysInfoFileManager.cpp

#include "SysInfoFileManager.h"

namespace SysInfo
{
        SysInfoFileManager* SysInfoFileManager::instance()
        {
                if (!_pinstance)
                {
                        //Lock Mutex
                        if (!_pinstance)
                        {
                                static Sys=

InfoFileManager sysInfoFileManager;

_pinstance=

= &sysInfoFileManager;

                        }
                }
                return _pinstance;
        }

}

I am getting follwing error. Any suggestion would of great help.

Error 1 error LNK2005: "private: static class
SysInfo::SysInfoFileManager *
SysInfo::SysInfoFileManager::_pinstance" (?
_pinstance@SysInfoFileManager@SysInfo@@$$Q0PAV12@A) already defined in
SyinfoWebServerClass.obj SysInfoFileManager.obj

Error 2 fatal error LNK1169: one or more multiply defined =

symbols

found C:\Webserver\SyinfoWebServer\Debug\SyinfoWebServer.dll 1

Thanks
siddhu

Put this into the .cpp file:

SysInfo::SysInfoFileManager*
SysInfo::SysInfoFileManager::_pinstance = 0;

You are including SysInfoFileManager.h in SyinfoWebServerClass.h (and
hence SyinfoWebServerClass.cpp) and that causes re-definition. statics
must be defined only once.