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Static Members

Static Members. There can be only one. a static member variable in a class represents all objects of that class, doing so with one and only one value. // fraction.h class Fraction {   public:     Fraction(const int n=0, const int d=1) : m_Num (n) { setDen (d); }

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Static Members

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  1. Static Members

  2. There can be only one a static member variable in a class represents all objects of that class, doing so with one and only one value

  3. // fraction.h • class Fraction • { •   public: •     Fraction(const int n=0, const int d=1) : m_Num(n) { setDen(d); } •     void readin(); •     ... •     static double zero_tolerance; •   private: • intm_Numerator; • intm_Denominator; • }; • double Fraction::zero_tolerance = .0001;

  4. // fraction.h • class Fraction • { •   public: •     Fraction(const int n=0, const int d=1) : m_Num(n) { setDen(d); } •     void readin(); •     ... •     static double zero_tolerance; •   private: • intm_Numerator; • intm_Denominator; • }; • double Fraction::zero_tolerance = .0001; • // main.cpp • ... • Fraction f(3,10000); • if (static_cast<double>(f.getNumer())/f.getDenom() <= Fraction::zero_tolerance) • f.setNumer(0);

  5. // fraction.h • class Fraction • { •   public: •     static double zero_tolerance; •     ... •   private: •     void zeroize_if_close(); •     ... • }; • double Fraction::zero_tolerance = .0001; • // fraction.cpp • void Fraction::zeroize_if_close() • { •     if(static_cast<double>(m_Numerator)/m_Denominator <= zero_tolerance) • m_Numerator = 0; •     return; • }

  6. // fraction.cpp • void Fraction::zeroize_if_close() • { •     if(static_cast<double>(m_Numerator)/m_Denominator <= zero_tolerance) • m_Numerator = 0; •     return; • } • void Fraction::readin() • { • cout<<“enter numerator: ”; • cin>>m_Numerator; • cout<<“enter denominator: ”; • cin>>m_Denominator; • zeroize_if_close(); • return; • }

  7. Static Functions // fraction.h • class Fraction • { •   public: • static void reset_zero_tolerance(const double tol){zero_tolerance = tol;} • ... • }; • double Fraction::zero_tolerance = .0001; • // main.cpp • ... • Fraction::reset_zero_tolerance(.000001);

  8. End of Session

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