rational.cpp

《c＋＋大学教程实验指导书》源码

// rational.cpp
// member function definitions for rational.cpp
#include <iostream> 

using std::cout; 

#include "rational.h"

// constructor
Rational::Rational( int n, int d )
{
   numerator = n;
   denominator = d;

} // end class Rational constructor

// add rational numbers
Rational Rational::addition( const Rational &a )
{
   Rational t;

   t.numerator = a.numerator * denominator;
   t.numerator += a.denominator * numerator; 
   t.denominator = a.denominator * denominator;
   t.reduction();

   return t;

} // end function addition

// subtract rational numbers
Rational Rational::subtraction( const Rational &s )
{
   Rational t;

   t.numerator = s.denominator * numerator;
   t.numerator -= denominator * s.numerator;
   t.denominator = s.denominator * denominator;
   t.reduction();

   return t;

} // end function subtraction

// multiply rational numbers
Rational Rational::multiplication( const Rational &m )
{
   Rational t;

   t.numerator = m.numerator * numerator;
   t.denominator = m.denominator * denominator;
   t.reduction();

   return t;

} // end function multiplication

// divide rational numbers
Rational Rational::division( const Rational &v )
{
   Rational t;

   t.numerator = v.denominator * numerator;
   t.denominator = denominator * v.numerator;
   t.reduction();

   return t;

} // end function division

// print rational numbers
void Rational::printRational()
{
   if ( denominator == 0 )
      cout << "\nDIVIDE BY ZERO ERROR!!!\n";
   
   else if ( numerator == 0 )
      cout << 0;
   
   else
      cout << numerator << '/' << denominator;

} // end function printRational

// print rational numbers as doubles
void Rational::printRationalAsDouble() 
{  
   cout << static_cast< double >( numerator ) / denominator; 

} // end function printRationalAsDouble

// helper function reduction definition
void Rational::reduction()
{
   int smallest; 

   smallest = numerator < denominator ? numerator : denominator;

   int gcd = 0;  // greatest common divisor

   for ( int loop = 2; loop <= smallest; ++loop )
   
      if ( numerator % loop == 0 && denominator % loop == 0 )
         gcd = loop;

   if ( gcd != 0 ) {
      numerator /= gcd;
      denominator /= gcd;
   
   } // end if

} // end helper function reduction

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