error LNK2005 not getting to solution to solve the problem - c++

Question

i am new to C++ need some help on this
mainclinet.CPP
#include "client.h"
#include "config.h*"
int main(){
g_pClientSampleConfig = new ClientSampleConfig;
g_pUaSession = NULL;
g_pCallback = NULL;
g_nsIndex = OpcUa_UInt16_Max;
g_nsIndex2 = OpcUa_UInt16_Max;
client();
}
function client() is declared in this files mainclient.CPP
client.h
OpcUa_UInt16 g_nsIndex2;
ClientSampleConfig* g_pClientSampleConfig = NULL;
UaSession* m_pSession;
void Connection_Initialzation();
config.cpp
ClientSampleConfig::ClientSampleConfig()
{
//some code
}
ClientSampleConfig::~ClientSampleConfig()
{
}
config.h
class ClientSampleConfig
{
public:
ClientSampleConfig();
~ClientSampleConfig();
}
the problem is i created a new file called clinet_start.cpp
in which i am defined the client(); with return type void when i trying to include the clinet.h in clinet_start.cpp it's giving the linker Error 2005 *class UaClientSdk::UaSession * g_pUaSession"* redefined i need help in this

Answer 1

I suggest you could refer to the Doc:Linker Tools Error LNK2005
If mainclinet.CPP and clinet_start.cpp include clinet.h , then both are compiled with your definition of client(), so both object files will contain code for client(). When the linker gathers all the functions, he sees that client() is defined in two object files and does not know which one to use. Thus the linker raises an LNK2005.
There are two solutions for you:
1,If you want client() to be inlined, you could try to use Inline Functions (C++)
2,If you don't care about inlining, you could try to use extern (C++)