#include <iostream.h>

/** pos_int - Create positive integers class

  Written by: Charles Severance - Thu Dec 23 17:02:01 EST 1993

*/

class Posint {
  private:
    int value;
  public:
    Posint(int initial = 0) { value = initial; } // Constructor 

    void operator = (int i) { 
      cout << "Assigning a value=" << i << "\n"; 
      if ( i < 0 ) {
        cout << "Error value less than zero\n";
        value = 0;
      } else {
        value = i;
      }
    }

    operator int () const { return(this->value); }  // Converting to integer

    void operator = (Posint pi) { 
      cout << "Copying " << pi.value<< " into a posint\n";
      value = pi.value;
    }

    Posint operator + (int i) {
      int tmp;
      Posint tpos;
      cout << "Adding " << i << " to a posint\n";
      tmp = value + i;
      tpos.value = 0;
      if ( tmp < 0 ) {
        cout << "Error result less than zero\n";
      } else {
        tpos.value = tmp;
      }
      return tpos;
    }

    Posint operator + (Posint pi) {
      Posint tpos;
      cout << "Adding two Posints\n";
      tpos = value + pi.value;
      return ( tpos );
    }

    int operator < (int i) {
      cout << "Comparing a posint = " << this->value ;
      cout << " and an int = " << i << "\n";
      return ( this->value < i ) ;
    }

 
    friend ostream & operator << ( ostream & os, const Posint pi);
    friend istream & operator >> ( istream & is, Posint & pi);

  };

ostream & operator << ( ostream & os, const Posint pi) {
  os << "[" << pi.value << "]" ;
  return os;
}

istream & operator >> ( istream & is, Posint & pi) {
  int tmp;
  is >> tmp;
  while( tmp < 0 ) {
    cout << "Error, please enter a positive number\n";
    is >> tmp;
  }
  pi.value = tmp;
  return is;
}
main () {

  Posint pi,pj;
  int i;
 
  pi = 1;

  pi = -1;

  pi = 4;

  pj = pi + 5;

  i = 2 + pi;

  cout << "A Posint value" << pj << "\n";

  cout << " Enter a Posint ";
 
  cin >> pi;

  cout << "You typed " << pi << "\n";

  cout << "\n";

  for(pi=0; pi < 10; pi = pi + 2 ) {
    cout << "Looping - current value = " << pi << "\n" ;
  }

}