// X.h
namespace N
{
class X
{
public:
void f();
};
class Y;
}
// X.cpp
#include "X.h"
namespace N
{
X *x = 0;
void X::f() { /*...*/ }
//methods in Y that needs x.
}
// main.cpp
#include "X.h"
extern N::X *x;
x = new N::X;
x->f();extern problems (c++)
Author
I'm trying to have a global object(not really global, should be in a namespace) of class X which is in namespace N.
The object doesn''t exist. extern tells the compiler to look for its definition elsewhere; have you defined it anywhere?
Typically, this is solved by placing the extern declaration in a header file that will be included in multiple places and placing the instance definition in the implementation file where the object can be said to "live".
Typically, this is solved by placing the extern declaration in a header file that will be included in multiple places and placing the instance definition in the implementation file where the object can be said to "live".
You''re putting not only the class definition, but also the global variable, in the namespace N. Therefore, when declaring it extern, you''ll have to declare it as
"Sneftel is correct, if rather vulgar." --Flarelocke
N::X* N::x. "Sneftel is correct, if rather vulgar." --Flarelocke
Have you tried adding "extern X * x;" inside the namespace block, in X.h ? This might work, you would only need to include X.h to be able to use the global.
Victor Nicollet, INT13 game programmer 
This topic is closed to new replies.
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