Question

Inside General.h

#ifndef GENERAL
#define GENERAL
namespace counternamespace{
    int upperbound;
    int lowerbound;
}
#endif

Inside Analyzer.h

#ifndef ANALYZER
#define ANALYZER
#include"General.h"

class Analyzer
{
public :
     int var ;
     int func();
};
#endif

Inside Test.h

#ifndef TEST
#define TEST
#include"Analyzer.h" //Error
class Test2
{
public:
    Test2(void);

public:
    ~Test2(void);
};
#endif

In the above code when I don’t add Analyzer inside Test.h everything is working fine. But after adding its showing the following linker error.

1>Test2.obj : error LNK2005: "int counternamespace::lowerbound" (?lowerbound@counternamespace@@3HA) already defined in Analyzer.obj
2>Test2.obj : error LNK2005: "int counternamespace::upperbound" (?upperbound@counternamespace@@3HA) already defined in Analyzer.obj

I have added the #ifndef/#endif. Then where I am doing the mistake? Can anyone please let me know?

Answer 1

Inside General.h

#ifndef GENERAL
#define GENERAL
namespace counternamespace{
    extern int upperbound;
    extern int lowerbound;
}
#endif

Inside General.cpp

#include"General.h"
using namespace counternamespace ;
int counternamepace::upperbound = 12;
int counternamepace::lowerbound = 12;

Then do whatever needed .