7.1 The user interface

What do we want to do with a fraction?

• Initialize. A good default is $\frac{1}{1}$.
• Add, subtract, multiply, divide.
• Set the denominator and numerator.
• Get the denominator and numerator.
• Get the value as a floating point number.
• Simplify.

This user interface determines the public section of the class definition:

class Fraction
{
  public:
    Fraction(void); // initialization
    void add(const Fraction b, Fraction &sum);
    void sub(const Fraction b, Fraction &diff);
    void mult(const Fraction b, Fraction &product);
    void div(const Fraction b, Fraction &quotient);
    unsigned getDenominator(void);
    unsigned getNumerator(void);
    void setDenominator(unsigned den);
    void setNumerator(unsigned num);
    float getValue(void);
    void simplify(void);
};