multiple definition of error.

[kama1]

Hi,

I get multiple defs even if i do a ifndef around it. I need to get a couple of global variables in different files.

these are my test files:

//a.h

#ifndef _A_H_
#define _A_H_
int a;
void add();
#endif

//a.cpp
#include "a.h"

add() { a++; }

//main.cpp
#include "a.h"

void main() {
a=3;
add();
cout << a << endl;
}

bash-2.03$ g++ a.o main.cpp
/tmp/cccRvDFI.o(.data+0x0): multiple definition of `a'
a.o(.data+0x0): first defined here
bash-2.03$

/bjorn

 

[Cagliostro]

#ifndef _A_H_
#define _A_H_
extern int a;
extern void add();
#endif John Fill

ivfmd@mail.md

 

[smaniraja]

You have included the header file a.h in both (a.cpp & main.cpp) the cpp files. While building a project you will get this error because you have defined the variable 'a' in a.cpp and in main.cpp.

Declare the variable as extern int a; in the a.h and define it as 'int a' in a.cpp or in main.cpp.

Regards,
Maniraja S

 

[Cagliostro]

just use keyword extern in h files. John Fill

ivfmd@mail.md