C++: Abstract class & methods & inheritance

// A.h
#ifndef A_H
#define A_H
class A{
protected:
//attributes, fields, etc.
public:
//pure virtual function -- abstract
void Paint()=0;
} ;
#endif

//ChildA.h
#include "A.h"
//extends from A
class ChildA: public A{
protected:
public:
//implement Paint in this class
void Paint();
};