/* Learning C# by Jesse Liberty Publisher: O'Reilly ISBN: 0596003765 */ using System; class Fraction { private int numerator; private int denominator; // create a fraction by passing in the numerator // and denominator public Fraction(int numerator, int denominator) { this.numerator=numerator; this.denominator=denominator; } // overloaded operator+ takes two fractions // and returns their sum public static Fraction operator+(Fraction lhs, Fraction rhs) { // like fractions (shared denominator) can be added // by adding thier numerators if (lhs.denominator == rhs.denominator) { return new Fraction(lhs.numerator+rhs.numerator, lhs.denominator); } // simplistic solution for unlike fractions // 1/2 + 3/4 == (1*4) + (3*2) / (2*4) == 10/8 // this method does not reduce. int firstProduct = lhs.numerator * rhs.denominator; int secondProduct = rhs.numerator * lhs.denominator; return new Fraction( firstProduct + secondProduct, lhs.denominator * rhs.denominator ); } // test whether two Fractions are equal public static bool operator==(Fraction lhs, Fraction rhs) { if (lhs.denominator == rhs.denominator && lhs.numerator == rhs.numerator) { return true; } // code here to handle unlike fractions return false; } // delegates to operator == public static bool operator !=(Fraction lhs, Fraction rhs) { return !(lhs==rhs); } // tests for same types, then delegates public override bool Equals(object o) { if (! (o is Fraction) ) { return false; } return this == (Fraction) o; } // return a string representation of the fraction public override string ToString() { String s = numerator.ToString() + "/" + denominator.ToString(); return s; } } public class TesterOperatorOverride { static void Main() { Fraction f1 = new Fraction(3,4); Console.WriteLine("f1: {0}", f1.ToString()); Fraction f2 = new Fraction(2,4); Console.WriteLine("f2: {0}", f2.ToString()); Fraction f3 = f1 + f2; Console.WriteLine("f1 + f2 = f3: {0}", f3.ToString()); Fraction f4 = new Fraction(5,4); if (f4 == f3) { Console.WriteLine("f4: {0} == F3: {1}", f4.ToString(), f3.ToString()); } if (f4 != f2) { Console.WriteLine("f4: {0} != F2: {1}", f4.ToString(), f2.ToString()); } if (f4.Equals(f3)) { Console.WriteLine("{0}.Equals({1})", f4.ToString(), f3.ToString()); } } }