Question

BaseClass.h

class BaseClass
{
 ...
};

SubClass.h

#include "BaseClass.h"
class SubClass : public BaseClass
{
 ...
};

---

MyApp.h

class BaseClass;
class SubClass;
class MyApp
{
 SubClass *pObject;

 BaseClass *getObject()
 {
  return pObject;
 }
};

I get a compiler error: error C2440: ‘return’ : cannot convert from ‘SubClass *’ to ‘BaseClass *’

Why doesn’t it work, surely you can automatically convert to a base-class without any casting?

Answer 1

In "MyApp.h", you only have forward declarations of the classes, so it’s not known that one derives from the other. You will need to include the "SubClass.h" before the body of getObject(); either include it from "MyApp.h", or move the body of getObject() into a source file and include it from there.