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
#ifndef RFRACTION_HPP
#define RFRACTION_HPP
// header file of the base class
#include "frac.hpp"
// **** BEGIN namespace CPPBook ********************************
namespace CPPBook {
/* class RFraction
* - derived from Fraction
* - new no access to inherited members
* (public remains public)
* - suitable for further inheritance
*/
class RFraction : public Fraction {
protected:
bool reducible; // true: fraction is reducible
// auxiliary function: returns the GCD of the numerator and denominator
unsigned gcd() const;
public:
/* default constructor, and one- and two-parameter constructor
* - parameters are passed to the Fraction constructor
*/
RFraction (int n = 0, int d = 1) : Fraction(n,d) {
reducible = (gcd() > 1);
}
// multiplicative assignment (reimplemented)
virtual const RFraction& operator*= (const Fraction&);
// input from a stream (reimplemented)
virtual void scanFrom(std::istream&);
// reduce fraction
virtual void reduce();
// test reducibility
virtual bool isReducible() const {
return reducible;
}
};
} // **** END namespace CPPBook ********************************
#endif // RFRACTION_HPP