C++程序设计讲义

// Program rational.cpp #include <iostream> #include <string> #include "rational.h" using namespace std; // default constructor Rational::Rational() { SetNumerator(0); SetDenominator(1); } // (numer, denom) constructor Rational::Rational(int numer, int denom) { SetNumerator(numer); SetDenominator(denom); } // Rational: copy constructor Rational::Rational(const Rational &r) { int a = r.GetNumerator(); int b = r.GetDenominator(); SetNumerator(a); SetDenominator(b); } // Rational: destructor Rational::~Rational() { // no body needed } // get the numerator int Rational::GetNumerator() const { return NumeratorValue; } // get the denominator int Rational::GetDenominator() const { return DenominatorValue; } // set the numerator void Rational::SetNumerator(int numer) { NumeratorValue = numer; } // set the denominator void Rational::SetDenominator(int denom) { if (denom != 0) { DenominatorValue = denom; } else { cerr << "Illegal denominator: " << denom << "using 1" << endl; DenominatorValue = 1; } } // adding Rationals Rational Rational::Add(const Rational &r) const { int a = GetNumerator(); int b = GetDenominator(); int c = r.GetNumerator(); int d = r.GetDenominator(); return Rational(a*d + b*c, b*d); } // subtracting Rationals Rational Rational::Sub(const Rational &r) const { int a = GetNumerator(); int b = GetDenominator(); int c = r.GetNumerator(); int d = r.GetDenominator(); return Rational(a*d - b*c, b*d); } // multiplying Rationals Rational Rational::Multiply(const Rational &r) const { int a = GetNumerator(); int b = GetDenominator(); int c = r.GetNumerator(); int d = r.GetDenominator(); return Rational(a*c, b*d); } // dividing Rationals Rational Rational::Divide(const Rational &r) const { int a = GetNumerator(); int b = GetDenominator(); int c = r.GetNumerator(); int d = r.GetDenominator(); return Rational(a*d, b*c); } // Rational: assignment operator Rational& Rational::operator=(const Rational &r) { int a = r.GetNumerator(); int b = r.GetDenominator(); SetNumerator(a); SetDenominator(b); return *this; } /* void Rational::operator=(const Rational &r) { int a = r.GetNumerator(); int b = r.GetDenominator(); SetNumerator(a); SetDenominator(b); return; } */ // inserting a Rational void Rational::Insert(ostream &sout) const { sout << GetNumerator() << '/' << GetDenominator(); return; } // extracting a Rational void Rational::Extract(istream &sin) { int numer; int denom; char slash; sin >> numer >> slash >> denom; SetNumerator(numer); SetDenominator(denom); return; } // adding Rationals Rational operator+(const Rational &r, const Rational &s) { return r.Add(s); } // subtracting Rationals Rational operator-(const Rational &r, const Rational &s) { return r.Sub(s); } // multiplying Rationals Rational operator*(const Rational &r, const Rational &s) { return r.Multiply(s); } // dividing Rationals Rational operator/(const Rational &r, const Rational &s) { return r.Divide(s); } // inserting a Rational ostream& operator<<(ostream &sout, const Rational &r) { r.Insert(sout); return sout; } // extracting a Rational istream& operator>>(istream &sin, Rational &r) { r.Extract(sin); return sin; } int main() { Rational r; Rational s; cout << "Enter 1st rational number (a/b): "; cin >> r; cout << "Enter 2nd rational number (a/b): "; cin >> s; Rational tr(r); Rational ts = s; Rational tts; tts = s; ts = tts = r; Rational Sum = r + s; Rational Difference = r - s; Rational Product = r * s; Rational Ratio = r / s; cout << r << " + " << s << " = " << Sum << endl; cout << r << " - " << s << " = " << Difference << endl; cout << r << " * " << s << " = " << Product << endl; cout << r << " / " << s << " = " << Ratio << endl; return 0; }