#include <iostream.h>
#include <string.h>

// ---------------------------------------------------------------------------
// Class Definitions
// ---------------------------------------------------------------------------
class entity
{
	private:
		static int	current_id;
		int			entity_id;

	protected:
		int			getid()			{return entity_id;}

	public:
		entity()	{ entity_id = current_id; current_id++; }
		virtual int id() = 0;
};

int entity::current_id = 0;

class person : public entity
{
	private:
       char			*name;
       int			tel;
	
	public:
       person(char* str = NULL, int i = 0);
       int			id()			{return getid();};
       void virtual print();
};

class student : virtual public person
{
	private:
		char		*degree;

	protected:
		void		_print();

	public:
		student(char* str, char* d = NULL, int t = 0);
		void		print();
};

class employee : virtual public person
{
	private:
		char		*department;

	protected:
		void		_print();

	public:
		employee(char*, char* d = NULL, int i = 0);
		void		print();
};

class ta : public student, public employee
{
	private:
		char		*duty;

	public:
		ta(	char* n,
			char* deg = NULL, 
			char* dept = NULL, 
			char* work = NULL,
			int i = 0);
		void	print();
};

// ---------------------------------------------------------------------------
// constructors and member functions
// ---------------------------------------------------------------------------
person::person(char* str, int i) : entity()
{
	if (str != NULL)
	{
		name = new char[strlen(str)+1];
        strcpy(name, str);
	}
	else 
		name = NULL;
	tel = i;
}

void person::print()
{
	cout << "name: " << name << endl;
	cout << "tel: "  << tel  << endl;
	cout << "id:   " << id() << endl;
}

student::student(char* n, char* d, int i) : person(n, i)
{
	if (d != NULL)
	{
		degree = new char[strlen(d)+1];
		strcpy(degree, d);
	}
	else
		degree = NULL;
}

void student::_print()
{
	cout << "Degree : " << degree << endl;
}

void student::print()
{
	person::print();
	_print();
}

employee::employee(char* n, char* d, int i) : person(n, i)
{
	if (d != NULL)
	{
		department = new char[strlen(d)+1];
		strcpy(department, d);
    } 
	else 
		department = NULL;
}

void employee::_print()
{
	cout << "Department : " << department << endl;
}

void employee::print()
{
	person::print();
    _print();
}

ta::ta(char* n, char* deg, char* dept, char* work, int t)
   : student(n, deg, t), employee(n, dept, t*10), person(n, t)
{
	if (work != NULL)
	{
		duty = new char[strlen(work)+1];
        strcpy(duty, work);
    }
	else
		duty = NULL;
}

void ta::print()
{
	person::print();
	student::_print();
	employee::_print();
	cout << "duty: " << duty << "\n";
}

// ---------------------------------------------------------------------------
// Main
// ---------------------------------------------------------------------------
void main(void)
{
       person   p1("William", 101);
       student  s1("Paul", "Honour", 102);
       employee e1("Steve", "Dept. of CS", 103);
       ta       t1("Albert", "MS", "CS", "C53", 104);

	   cout << t1.student::id()	<< endl;
	   cout << t1.employee::id()	<< endl;
	   cout << t1.id()	<< endl;
       p1.print();
       s1.print();
       e1.print();
       t1.print();
}