The following code example is taken from the book
Object-Oriented Programming in C++
by Nicolai M. Josuttis, Wiley, 2002
© Copyright Nicolai M. Josuttis 2002
// header file for min() and abs()
#include <algorithm>
#include <cstdlib>
// include header file of the separate class
#include "rfrac.hpp"
// **** BEGIN namespace CPPBook ********************************
namespace CPPBook {
/* gcd()
* - greatest common divisor of numerator and denominator
*/
unsigned RFraction::gcd() const
{
if (numer == 0) {
return denom;
}
/* determine the greatest number that divides, without remainder,
* the denominator and the numerator
*/
unsigned divisor = std::min(std::abs(numer),denom);
while (numer % divisor != 0 || denom % divisor != 0) {
--divisor;
}
return divisor;
}
/* reduce()
*/
void RFraction::reduce()
{
// if reducible, divide numerator and denominator by CGD
if (reducible) {
int divisor = gcd();
numer /= divisor;
denom /= divisor;
reducible = false; // no longer reducible
}
}
/* operator *=
* - reimplemented
*/
const RFraction& RFraction::operator*= (const RFraction& f)
{
// as with the base class:
numer *= f.numer;
denom *= f.denom;
// still reduced?
if (!reducible) {
reducible = (gcd() > 1);
}
return *this;
}
/* scanFrom()
*/
void RFraction::scanFrom(std::istream& strm)
{
Fraction::scanFrom(strm); // call scanFrom() of the base class
reducible = (gcd() > 1); // test reducibility
}
} // **** END namespace CPPBook ********************************