データ構造、アルゴリズム、アプリケーション--クラス

curr1.h

#ifndef Currency_
#define Currency_

#include <iostream>
#include <stdlib.h>
using namespace std;

enum sign {plus, minus};

class Currency {
// public           
   public:
//constructor            ，        ，
      Currency(sign s = plus, unsigned long d = 0,
                              unsigned int c = 0);
      // destructor    Currency                 ，       
      ~Currency() {}
      bool Set(sign s, unsigned long d,
                       unsigned int c);
      bool Set(float a);
      sign Sign() const {return sgn;}
      unsigned long Dollars() const {return dollars;}
      unsigned int Cents() const {return cents;}
      Currency Add(const Currency& x) const;
      Currency& Increment(const Currency& x);
      void Output() const;
// private               ，                  
   private:
      sign sgn;
      unsigned long dollars;
      unsigned int cents;
};
//       ，             Currency：：，       Currency      
Currency::Currency(sign s, unsigned long d,
                           unsigned int c)
{// Create a Currency object.
   if (c > 99)
      {// too many cents
       cerr << "Cents should be < 100" << endl;
	//       
       exit(1);}
   
   sgn = s; dollars = d; cents = c;
}

//        
bool Currency::Set(sign s, unsigned long d,
                           unsigned int c) 
{// Reset value.
   if (c > 99) return false;
   sgn = s; dollars = d; cents = c;
   return true;
}
   //              
bool Currency::Set(float a) 
{// Reset value.
   if (a < 0) {sgn = minus; a = -a;}
   else sgn = plus;
   dollars = a; // extract integer part
   // get two decimal digits
   cents = (a + 0.001 - dollars) * 100;
   return true;
}

Currency Currency::Add(const Currency& x) const
{// Add x and *this.
   long a1, a2, a3;
   Currency ans;
   // convert invoking object to signed integers
   a1 = dollars * 100 + cents;
   if (sgn == minus) a1 = -a1;
   
   // convert x to signed integer
   a2 = x.dollars * 100 + x.cents;
   if (x.sgn == minus) a2 = -a2;
   
   a3 = a1 + a2;
    
   // convert to currency representation
   if (a3 < 0) {ans.sgn = minus; a3 = -a3;}
   else ans.sgn = plus;
   ans.dollars = a3 / 100;
   ans.cents = a3 - ans.dollars * 100;
   
   return ans;
}
/*
                             ，          public，                   
*/

Currency& Currency::Increment(const Currency& x)
{// Increment by x.
   *this = Add(x);
   return *this;
}

void Currency::Output() const
{// Output currency value.
   if (sgn == minus) cout << '-';
   cout << '$' << dollars << '.';
   if (cents < 10) cout << "0";
   cout << cents;
}

#endif

curr1.cpp

// test currency class                        

#include <iostream>
#include <string>
#include "curr1.h"
using namespace std;
void main(void)
{
   Currency g, h(plus, 3, 50), i, j;
   g.Set(minus, 2, 25);
   i.Set(-6.45);
   j = h.Add(g);
   j.Output(); cout << endl;
   i.Increment(h);
   i.Output(); cout << endl;
   j = i.Add(g).Add(h);
   j.Output(); cout << endl;
   j = i.Increment(g).Add(h);
   j.Output(); cout << endl;
   i.Output(); cout << endl;
}