/*********************************************************************
  C201 Computer Programming II
  Fall 2006
  Dana Vrajitoru &

  A class to represent large integer numbers.

**********************************************************************/

#ifndef NUMBER_H
#define NUMBER_H

#include <iostream>
using namespace std;

enum Sign_ty {plus_id, minus_id=-1};
const int MAX_SIZE = 50;

class Number {
 private:
  short int digits[MAX_SIZE];
  int size;
  Sign_ty sign;

  // Some private class methods:
  // Add the digits in the two numbers regardless of the sign.
  void Add_digits(const Number &data);
  // Subtract the digits in the two numbers regardless of the sign.
  void Subtract_digits(const Number &data);
  // Compare the digits in the two number regardless of the sign. The
  // function returns -1 if the target object is less than the number
  // data, 0 if they are identical, and +1 if the target object is
  // larger than the data.
  int Compare_digits(const Number &data) const;
  // Multiplication by a single digit. We need this for the operator *.
  void Multiply(const short int d);
  // Shifts the digits to the left. This is equivalent to a
  // multiplication by 10. It moves digits[0] to digits[1], digits[1]
  // to digits[2], and so on. It must start from the end of the number
  // (position size -1) and go backwards. It must add a 0 digit at
  // position 0.
  void Shift_left();

 public:
  // Constructors
  // Default constructor: intializes all digits to 0.
  Number();
  // Copy constructor.
  Number(const Number &data);
  // Converting a simple number to an object of the class.
  Number(const int n);
  // Converting a string to an object of the class.
  Number(const char *s);

  // We may need to reset all the digits to 0.
  void Reset();

  // Accessor functions.
  int length() const;

  // Operators

  // Assignment operator. One for each type.
  Number &operator=(const Number &data);
  Number &operator=(const int n);
  Number &operator=(const char *s);

  // Arithmetic operations.
  // Addition
  const Number operator+(const Number &data) const;
  // Subtraction
  const Number operator-(const Number &data) const;
  // Sign change
  const Number operator-() const;
  // Multiplication
  const Number operator*(const Number &data) const;
  // Division
  const Number operator/(const Number &data) const;
  // Modulus
  const Number operator%(const Number &data) const;

  // All of these operations with the matching assignment
  // Arithmetic operations.
  // Addition
  Number &operator+=(const Number &data);
  // Subtraction
  Number &operator-=(const Number &data);
  // Multiplication
  Number &operator*=(const Number &data);
  // Division
  Number &operator/=(const Number &data);
  // Modulus
  Number &operator%=(const Number &data);

  // Incrementing operator. It is used as in ++n.
  Number &operator++();
  // Decrementing operator. It is used as in --n.
  Number &operator--();

  // Comparison operators 
  bool operator<(const Number &data) const;
  bool operator<=(const Number &data) const;
  bool operator>(const Number &data) const;
  bool operator>=(const Number &data) const;
  bool operator==(const Number &data) const;
  bool operator!=(const Number &data) const;

  // Input - output operators.
  friend ostream &operator<<(ostream &out, const Number &data);
  friend istream &operator>>(istream &in, Number &data);

};

#endif