ex8_4.cpp

《C++面对对象程序设计》的所有源代码和部分头文件

// ex8_4.cpp
// overloaded arithmetic operators work with type Int
#include <iostream>
using namespace std;
#include <process.h>                     //for exit()
////////////////////////////////////////////////////////////////
class Int
   {
   private:
      int i;
   public:
      Int() : i(0)                       //no-arg constructor
         {  }
      Int(int ii) : i(ii)                //1-arg constructor
         {  }                            //   (int to Int)
      void putInt()                      //display Int
         { cout << i; }
      void getInt()                      //read Int from kbd
         { cin >> i; }
      operator int()                     //conversion operator
         { return i; }                   //   (Int to int)
      Int operator + (Int i2)            //addition
         { return checkit( long double(i)+long double(i2) ); }
      Int operator - (Int i2)            //subtraction
         { return checkit( long double(i)-long double(i2) ); }
      Int operator * (Int i2)            //multiplication
         { return checkit( long double(i)*long double(i2) ); }
      Int operator / (Int i2)            //division
         { return checkit( long double(i)/long double(i2) ); }

      Int checkit(long double answer)           //check results
         {
         if( answer > 2147483647.0L || answer < -2147483647.0L )
            { cout << "\nOverflow Error\n"; exit(1); }
         return Int( int(answer) );
         }
   };
////////////////////////////////////////////////////////////////
int main()
   {
   Int alpha = 20;
   Int beta = 7;
   Int delta, gamma;

   gamma = alpha + beta;                  //27
   cout << "\ngamma="; gamma.putInt();
   gamma = alpha - beta;                  //13
   cout << "\ngamma="; gamma.putInt();
   gamma = alpha * beta;                  //140
   cout << "\ngamma="; gamma.putInt();
   gamma = alpha / beta;                  //2
   cout << "\ngamma="; gamma.putInt();

   delta = 2147483647;
   gamma = delta + alpha;                 //overflow error
   delta = -2147483647;
   gamma = delta - alpha;                 //overflow error

   cout << endl;
   return 0;
   }