Avoid re-definition in C++

Question

I would like to avoid re-definition from two different include files as follows:

File ABC.h

extern int v=1;

File foo.h

#include "ABC.h"
class Foo
#ifdef BLA
: public ABC
#endif

{
    ...
};

File bar.h

extern int v=3;

Main:

#define BLA
#include <foo.h>
#include <bar.h>

Basically foo is a class written by me, and bar is a third-party library. But it doesn't seem to work. How should I solve the problem?

Sorry, it's a bit hard to describe, the example is kind of bad as the conflicted parts are actually not variables, but something like #define and wrapped in big blocks of code (error message is: "multiple definition of `__vector_17'"). Is there a way to solve it without using a namespace?

...Or giving your own variable a different name? To reflect its different function? — Beta, Apr 10 '13 at 20:41
Both ABC.h and bar.h has some really complicated stuff inside that I'd rather avoid :( — Xun Yang, Apr 10 '13 at 20:43
Would this SO entry be useful to you? http://stackoverflow.com/questions/6378817/variable-redefinition-embedded-c — joce, Apr 10 '13 at 20:47

score 1 · Answer 1 · edited Apr 12 '13 at 09:50

1

Using a namespace you can solve this problem:

namespace foo
{
    int val =1;
}

namespace bar
{
    int val =3;
}

using namespace foo;

int x = val; //Now x will be assigned with 1

edited Apr 12 '13 at 09:50

Peter Mortensen

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answered Apr 10 '13 at 20:42

shivakumar

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score 0 · Answer 2 · edited Apr 12 '13 at 09:51

0

A namespace is what you need:

namespace foo
{
    int v =100;
}

namespace bar
{
    int v =500;
}

edited Apr 12 '13 at 09:51

Peter Mortensen

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answered Apr 10 '13 at 20:46

4pie0

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Avoid re-definition in C++

File ABC.h

File foo.h

File bar.h

Main:

2 Answers2