c++ - Circular dependency -

i have class called point , other namespace containing tree class. tree balanced binary search tree, , uses function compare compare keys , puts them in right place. tree contains points, , each point have know tree belongs to, tried add pointer tree in point class this:

class point{    public:    double x, y;    std::set<std::multiset<point,tree::compare()>*>s; //tree name of namespace // other data } 

my problem since tree uses point.h(because stores points) cant add layerthree.h cant use tree::compare() in point.h. tried add new file cmp.h , put compare function in it, did not help. should do?

edit: can not put both tree , point class in same file because there other files needs include point.h

as jepessen mentioned need forward declaration. here example:

class depends on class b , class b depends on class a, use forward declaration this:

in class "b.h":

#include "a.h"  class b {    //do stuff }; 

and in class "a.h":

 // forward declaration of class b, tells compiler not worry   // class b somewhere later in compilation class b declared class b;  class {    //do stuff };