Write A C++ Program Using A Friend to Overload ++ or – –

#include <iostream.h> 
 #include<conio.h> 
 class Values 
 { 
         int a,b; 
                  public: 
                             Values() {} 
                             Values(int aa,int bb) 
                          { 
                             a=aa; 
                             b=bb; 
                          } 
                             void show() 
                         { 
                              cout <<a <<" "; 
                              cout <<b <<"\n"; 
                          } 
                             Values operator=(Values p2); 
                             friend Values operator++(Values &p); 
                             friend Values operator-(Values &p); 
 }; 
                            Values Values::operator=(Values p2) 
             { 
                            a =p2.a; 
                            b =p2.b; 
                            return *this; 
                  } 
                           //friend;use a reference. 
                           Values operator++(Values &p) 
                  { 
                            p.a++; 
                            p.b++; 
                            return p; 
                  } 
                            //lip- a friend;use reference 
                            Values operator-(Values &p) 
                 { 
                             p.a--; 
                             p.b--; 
                             return p; 
                  } 
                             void main() 
         { 
                             clrscr(); 
                             Values v1 (20,30),v2; 
                             v1.show();  
                             ++v1; 
                             v1.show(); 
                             v2 =++v1 ; 
                             v2.show(); 
                             -v2; 
                              v2.show(); 
                              getch(); 
          }