#include <conio.h>

#include <iostream.h>

#include <stdio.h>

class TIN_HIEU

{

int tancao,tanthap,trungbinh;

public:

TIN_HIEU();

TIN_HIEU operator+(TIN_HIEU);

TIN_HIEU operator-(TIN_HIEU);

friend ostream & operator<<(ostream &os,TIN_HIEU &b);

friend istream & operator>>(istream &is,TIN_HIEU &b);

};

//---------------------

TIN_HIEU::TIN_HIEU()

{

tancao=0;

tanthap=0;

trungbinh=0;

}

//--------------------

ostream & operator<<(ostream &os,TIN_HIEU &b)

{

os<<"Tan cao:"<<b.tancao<<endl<<"Tan thap:"<<b.tanthap<<endl<<"Trung binh: "<<b.trungbinh<<endl;

return os;

}

//----------------------

istream & operator>>(istream & is,TIN_HIEU &b)

{

cout<<"Nhap tan cao:";

is>>b.tancao;

cout<<"Nhap tan thap: ";

is>>b.tanthap;

cout<<"Nhap trung binh: ";

is>>b.trungbinh;

return is;

}

//----------------------

TIN_HIEU TIN_HIEU::operator+(TIN_HIEU p)

{

TIN_HIEU q;

q.tancao=tancao+p.tancao;

q.tanthap=tanthap+p.tanthap;

q.trungbinh=trungbinh+q.trungbinh;

return q;

}

//------------------------

TIN_HIEU TIN_HIEU::operator-(TIN_HIEU p)

{

TIN_HIEU q;

q.tancao=tancao-p.tancao;

q.tanthap=tanthap-p.tanthap;

q.trungbinh=trungbinh-p.trungbinh;

return q;

}

//------------------------

void main()

{

clrscr();

TIN_HIEU a,b;

cout<<"Nhap TIN_HIEU a: "<<endl;

cin>>a;

cout<<"Nhap TIN_HIEU b: "<<endl;

cin>>b;

cout<<"Tong la "<<endl<<a+b;

cout<<"----------------"<<endl;

cout<<"Hieu la "<<endl<<a-b;

getch();

}