Classes and operator overload

Question

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using System;


class Fraction
{
   int wholeNumber;
   int numerator;
   int denominator = 1;


   public int WholeNumber
   {
      get{ return wholeNumber; }
      set{ wholeNumber = value; }
   }


   public int Numerator
   {
      get{ return numerator; }
      set{ numerator = value; }
   }


   public int Denominator
   {
      get{ return denominator; }
      set{ denominator = (value != 0) ? value : 1; }
   }


   public Fraction(int wholeNumber, int numerator, int denominator)
   {
      this.wholeNumber = wholeNumber;
      this.numerator = numerator;
      this.Denominator = denominator; // use the property to validate here 
   }


   public Fraction(int numerator, int denominator)
   {
      this.wholeNumber = 0;
      this.numerator = numerator;
      this.Denominator = denominator; // use the property to validate here
   }


   public Fraction()
   {
      this.wholeNumber = 0;
      this.numerator = 0;
      this.denominator = 1;
   }


   public void Reduce()
   {
      if (numerator == 0)
      {
         denominator = 1;
         return;
      }
      int gcd = GetGCD(Math.Abs(numerator), Math.Abs(denominator));
      numerator /= gcd;
      denominator /= gcd;
   }


   public override string ToString()
   {
      return String.Format("{0} {1}/{2}", wholeNumber, numerator, denominator);
   }


   public static Fraction operator +(Fraction f1, Fraction f2)
   {
      f1.numerator += f1.wholeNumber * f1.denominator;
      f1.wholeNumber = 0;
      f2.numerator += f2.wholeNumber * f2.denominator;
      f2.wholeNumber = 0;
      int commonDenom = f1.denominator * f2.denominator;
      f1.numerator *= f2.denominator;
      f2.numerator *= f1.denominator;
      f1.denominator = commonDenom;
      f2.denominator = commonDenom;
      Fraction f3 = new Fraction(f1.numerator + f2.numerator, commonDenom); 
      f3.Reduce();
      if (Math.Abs(f3.numerator) >= Math.Abs(f3.denominator))
      {
         f3.wholeNumber += f3.numerator / f3.denominator;
         f3.numerator = f3.numerator % f3.denominator;
         if (f3.numerator == 0) f3.denominator = 1;
      }
      return f3;    
   }


   static int GetGCD(params int[] numbers)
   {
      // get the smallest number as the GCD can't be larger than that
      Array.Sort(numbers);
      int min = numbers[0];
      if (min < 1) throw new ArgumentException("The array can't include a number less than 1");
      if (min == 1) return 1; // GCD must be 1
      for(int i = min; i >= 1; i--)
      {
         int rem = min % i;
         if (rem > 0) continue; // 'i' can't be a factor of min
       
         bool isFactor = true;


         for(int j = 1; j < numbers.Length; j++)
         {
            int rem2 = numbers[j] % i;            
            if (rem2 > 0) // 'i' can't be a factor of numbers[j]
            {
               isFactor = false;
               break;
            }
         }


         if (isFactor) return i; // 'i' must be the GCD
      }
               
      return 1; // needed to keep compiler happy, but will never get to this line
   }
}


class FractionDemo
{
   static void Main()
   {
      Fraction f1 = new Fraction(12, 24);
      Console.Write("f1 = ");
      Console.WriteLine(f1);
      f1.Reduce();
      Console.Write("f1 now = ");
      Console.WriteLine(f1);
      Fraction f2 = new Fraction(4, 8, 16);
      Console.Write("f2 = ");
      Console.WriteLine(f2);
      f2.Reduce();
      Console.Write("f2 now = ");
      Console.WriteLine(f2);
      Fraction f3 = f1 + f2;
      Console.Write("f3 = f1 + f2 = ");
      Console.WriteLine(f3);
      Console.ReadKey();
   }
}