15.20.cpp

#include <iostream>

class Base
{
public:
	void pub_mem();
	void memfcn(Base &b) { b = *this; }
protected:
	int prot_mem;
private:
	char priv_mem;
};

struct Pub_Derv : public Base
{
	int f() { return prot_mem; }
	//char g() { return priv_mem; }
	void memfcn(Base &b) { b = *this; }
};

struct Priv_Derv : private Base
{
	int f1() const { return prot_mem; }
	void memfcn(Base &b) { b = *this; }
};

struct Prot_Derv : protected Base
{
	int f() const { return prot_mem; }
	void memfcn(Base &b) { b = *this; }
};

struct Derived_from_Public : public Pub_Derv
{
	int use_base()	{ return prot_mem; }
	void memfcn(Base &b) { b = *this; }
};

struct Derived_from_Private : public Priv_Derv
{
	//int use_base()	{ return prot_mem; }
	//void memfcn(Base &b) { b = *this; }
};

struct Derived_from_Protected : public Prot_Derv
{
	int use_base()	{ return prot_mem; }
	void memfcn(Base &b) { b = *this; }
};

int main()
{
	Pub_Derv d1;
	Priv_Derv d2;
	Prot_Derv d3;
	Derived_from_Public dd1;
	Derived_from_Private dd2;
	Derived_from_Protected dd3;
	Base *p = &d1;
	//p = &d2;
	p = &dd1;
	//p = &dd2;
	//p = &dd3;
	
	return 0;
}