import an external function

[Maximus]

How to import a function in another translation unit with a namespace? Let's
say we have two cpp files:

1.cpp

namesapce mu {

int func() { return 0;}

};


and in 2.cpp, I declare

namespace mu {

extern int func();

};

The compiler (VC 2005) complains that it can not find definition of func(),
obvisousely believing that the "extern" refers to a function in global
namespace.


I can get it work by declaring it in a header file shared by both files.
However, I only need this function definition in 2.cpp so that is not what I
really wanted.

 

[C C++ C++]

How to import a function in another translation unit with a namespace? Let's
say we have two cpp files:

1.cpp

namesapce mu {

int func() { return 0;}

};

and in 2.cpp, I declare

namespace mu {

extern int func();

};

The compiler (VC 2005) complains that it can not find definition of func(),
obvisousely believing that the "extern" refers to a function in global
namespace.

I can get it work by declaring it in a header file shared by both files.
However, I only need this function definition in 2.cpp so that is not what I
really wanted.

Though i am not very much sure, can you try extern int mu::func();

 

[Juha Nieminen]

How to import a function in another translation unit with a namespace? Let's
say we have two cpp files:

1.cpp

namesapce mu {

int func() { return 0;}

};


and in 2.cpp, I declare

namespace mu {

extern int func();

};

The compiler (VC 2005) complains that it can not find definition of func(),
obvisousely believing that the "extern" refers to a function in global
namespace.

Have you tried removing the "extern" keyword? That's how I always
declare functions in namespaces.

(I have to admit I don't know why "extern" would make it not work. I
always assumed it's kind of implied in all function declarations. I have
to admit I don't know if things change with namespaces.)

 

[James Kanze]

How to import a function in another translation unit with a
namespace? Let's say we have two cpp files:

namesapce mu {

int func() { return 0;}

and in 2.cpp, I declare

namespace mu {

extern int func();

The compiler (VC 2005) complains that it can not find
definition of func(), obvisousely believing that the "extern"
refers to a function in global namespace.

Obviously not. Post a compilable example of what doesn't work.
(Both of the files you post compile without problems.)

I can get it work by declaring it in a header file shared by
both files.

Which is the correct solution.

However, I only need this function definition in 2.cpp so that
is not what I really wanted.

It looks like what you should want to me. You have a function
defined in one translation unit. You want to use it in another.
The only acceptable solution is a header file, included in
*both* translation units.