rational.cpp

《c＋＋大学教程实验指导书》源码

// Chapter 8 of C++ How to Program
// rational.cpp 
#include <cstdlib>

#include <iostream> 

using std::cout; 
using std::endl; 

#include "rational.h"

// constructor
RationalNumber::RationalNumber( int n, int d )
{
   numerator = n;
   denominator = d;
   /* Write function call to reduction function */

} // end class RationalNumber constructor

/* Write definition for overloaded operator+ */

// function operator- definition
const RationalNumber RationalNumber::operator-(
   const RationalNumber &s )
{
   RationalNumber sub;

   sub.numerator = numerator * s.denominator - denominator *
      s.numerator;
   sub.denominator = denominator * s.denominator;
   sub.reduction();
   return sub;

} // end function operator- 

/* Write definition for overloaded operator * */

// function operator/ definition
const RationalNumber RationalNumber::operator/( 
   const RationalNumber &d )
{
   RationalNumber divide;

   if ( /* Write condition to test for zero numerator */ ) {  
      divide.numerator = numerator * d.denominator;
      divide.denominator = denominator * d.numerator;
      divide.reduction();

   } // end if

   else {
      cout << "Divide by zero error: terminating program\n";
      exit( 1 );   // cstdlib function

   } // end else

   return divide;

} // end function operator/

// function operator> definition
bool RationalNumber::operator>( const RationalNumber &gr ) const
{
   // compare double values of two rational numbers
   if ( static_cast< double >( numerator ) / denominator > 
        static_cast< double >( gr.numerator ) / gr.denominator )
      return true;

   else
      return false;

} // end function operator>

// function operator< definition
bool RationalNumber::operator<( const RationalNumber &lr ) const
{
   return !( *this > lr );

} // end function operator<

// function operator>= definition
bool RationalNumber::operator>=( const RationalNumber &rat ) const
{  
   return *this == rat || *this > rat;

} // end function operator>=

/* Write definition for operator <= */

/* Write definition for operator == */

/* Write definition for operator != */

// function printRational definition
void RationalNumber::printRational() const
{
   if ( numerator == 0 )         // print fraction as zero
      cout << numerator;

   else if ( denominator == 1 )  // print fraction as integer
      cout << numerator;

   else
      cout << numerator << '/' << denominator;

} // end function printRational

// function reduction definition
void RationalNumber::reduction()
{
   int smallest;
   int gcd = 1;  // greatest common divisor

   smallest = ( numerator < denominator ) ? numerator 
      : denominator;

   for ( int loop = 2; loop <= smallest; ++loop )

       if ( numerator % loop == 0 && denominator % loop == 0 )
          gcd = loop;

   numerator /= gcd;
   denominator /= gcd;

} // end function reduction




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