Programming Forums > Application Development > C++

kevin_cpp · May 15th, 2005, 1:20 AM

Hi all,

I'm trying to use the "namespace" feature of C++ but I'm getting linker errors (I'm using Visual Studios). It seems like the fix should be trivial but I don't know how to do it.

Here's what I'm doing:

-------- Main File --------------------

(Toggle Plain Text)

#include (the standard stuff)

#include "inner_file.h"
#include "outer_file.h"

int main()
{
inner::f();
...
outer::f();
}

-------- inner_file.h ------------

(Toggle Plain Text)

namespace inner
{
int A[10];
void f();
}

-------- inner_file.cpp ----------

(Toggle Plain Text)

#include "inner_file.h"
namespace inner
{
void f() { /* implementation */ }
}

Then I also have "outer_file.h" and "outer_file.cpp" but they're the same as the inner_files with the exception that the namespace is now "outer". When I compile it, I get a linker errorr saying that

inner::A already defined in main_file.obj
outer::A already defined in main_file.obj

(or something along those lines)

What am I doing wrong?

Thanks,

Kevin

uman · May 17th, 2005, 3:28 PM

The problem is that you're defining variables in .h files, which you're not supposed to do.

int A[10];

don't do that in a .h file. The problem has nothing to do with namespaces, which you are using correctly.

May 15th, 2005, 1:20 AM	#1
kevin_cpp Newbie Join Date: May 2005 Posts: 1 Rep Power: 0	C++ namespace question Hi all, I'm trying to use the "namespace" feature of C++ but I'm getting linker errors (I'm using Visual Studios). It seems like the fix should be trivial but I don't know how to do it. Here's what I'm doing: -------- Main File -------------------- (Toggle Plain Text) #include (the standard stuff) #include "inner_file.h" #include "outer_file.h" int main() { inner::f(); ... outer::f(); } #include (the standard stuff) #include "inner_file.h" #include "outer_file.h" int main() { inner::f(); ... outer::f(); } -------- inner_file.h ------------ (Toggle Plain Text) namespace inner { int A[10]; void f(); } namespace inner { int A[10]; void f(); } -------- inner_file.cpp ---------- (Toggle Plain Text) #include "inner_file.h" namespace inner { void f() { /* implementation / } } #include "inner_file.h" namespace inner { void f() { / implementation */ } } Then I also have "outer_file.h" and "outer_file.cpp" but they're the same as the inner_files with the exception that the namespace is now "outer". When I compile it, I get a linker errorr saying that inner::A already defined in main_file.obj outer::A already defined in main_file.obj (or something along those lines) What am I doing wrong? Thanks, Kevin

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May 17th, 2005, 3:28 PM	#2
uman Expert Programmer Join Date: Dec 2004 Posts: 794 Rep Power: 4	The problem is that you're defining variables in .h files, which you're not supposed to do. int A[10]; don't do that in a .h file. The problem has nothing to do with namespaces, which you are using correctly.

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Programming Forums > Application Development > C++

C++ namespace question