[Solved] Why isn’t C++ inheritance in multiple header and source files working?

You have a cycle in your header inclusion: MainProgram.h includes FileMgr.h FileMgr.h includes MgrBase.h MgrBase.h includes MainProgram.h You need to break this cycle using forward declarations. The rule in header files should be: if you only need to declare reference or pointer to a type X, forward declare X instead of including the header which … Read more