Fatal error LNK1169: one or more multiply defined symbols found

[A Former User]

Hello everybody;
I have a problem with my class when i call my class in more than once...
How can I solve it?

My error is :

@
1>------ Rebuild All started: Project: Project7, Configuration: Debug Win32 ------
1> stdafx.cpp
1> main.cpp
1> m2.cpp
1> m1.cpp
1>main.obj : error LNK2005: "class MyClass * Action" (?Action@@3PAVMyClass@@A) already defined in m2.obj
1>c:\users\Domain\documents\visual studio 2013\Projects\Project7\Debug\Project7.exe : fatal error LNK1169: one or more multiply defined symbols found
========== Rebuild All: 0 succeeded, 1 failed, 0 skipped ==========
@

My H1.h file :
@
#ifndef M1_H
#define M1_H

#include <iostream>

class MyClass
{
public:
MyClass();
~MyClass();

private:

public:
std::string P();

};

#endif

@

My H1.cpp file :

@
#include "stdafx.h"
#include "m1.h"

MyClass::MyClass() {}
MyClass::~MyClass() {}

std::string MyClass::P()

{

return "Test";
}

@

My H2.h file :

@
#ifndef M2_H
#define M2_H

#include <iostream>

class MyClass2
{
public:
MyClass2();
~MyClass2();

private:

public:
std::string P2();

};

#endif

@

My h2.cpp file :

@

#include "stdafx.h"
#include "m1.h"
#include "m2.h"

MyClass2::MyClass2() {}
MyClass2::~MyClass2() {}

MyClass * Action = new MyClass;

std::string MyClass2::P2()

{

return "Test";
}

@

and my main

@
#include "stdafx.h"
#include <iostream>
#include "m1.h"

using namespace std;

MyClass * Action = new MyClass;

int main()

{

getchar();

};
@

Who can help me for solve this problem , what happened after compile please explain this error to me :)

[mcosta]

Hi,

the problem is that you define two "global" objects with the same name

Action in main.cpp

Action in h2.cpp

in C++ "global" objects lives in the same namespace so you cannot use the same name.

[lutzhell]

Hi,

the more general question is: why do you need these "global" objects anyway especially in main? Since Action is a pointer it can be passed to any function without any relevant costs.