Wei,

include files are not inherited, they are only used compile time. If the derived class needs to use the the constants they have to know where they are found.

I have adopted using an include file for each classlib. This way if the classlib with the derived classes inherit from more than one classlib you can easily account for it:

* parentclasslib1.h
#define XYZ 0

* parentclasslib2.h
#define QWERTY 1

* classlibX.h (which derives from both 1 and 2
#include parentclasslib1.h
#include parentclasslib2.h

#define NewStuffForTheClassesInClasslibX "test"

This way each class that needs to have access to #define constants simply uses its own classlib.h file.

>Thanks. Is there anyway can make it easier? How does VFP implement the derived class?