/* rational numbers in C#, with C# specialties */
using System;

class rational
{
  private int num;
  private int dem;
  private int gcd(int a, int b) {if (a==0) return b; else return gcd(b%a,a);}

  // C# attributes - automates accessor/modifier operations:
  
  public int Numerator
  {
    get
     {
        return num; 
     } // accessor
    
    set
     {
        num = value;  // value is keyword in C#
     } // modifier
  } // Numerator property

  public int Denominator
  {
    get
     {
        return dem; 
     } // accessor
    
    set
     {
        if (value !=0) dem = value;  // value is keyword in C#
     } // modifier
  } // Denominator property

  public rational(int n, int d)  // constructor
    {  int g;
       num = n;  if (d!=0) dem = d; else dem = 1;
       g = gcd(num,dem);
       num = num/g;   dem = dem/g;      
    }  

  public void invert() 
    { if (num==0) return;
      int temp;
      temp = num;  num = dem; dem = temp;
    }

  public bool equals(rational other)
    { return num*other.dem == dem*other.num; }

  public void multx(rational b)
    {
      num = num*b.num;  dem = dem*b.dem;
    }
  public rational mult(rational b)
    { return new rational(num*b.num, dem*b.dem); }
 
  public override string ToString() { return (num + "/" + dem); }
}  // class rational

public class rats
{
 public static void Main(string[] aaa)
 {
  rational a, b;
  a = new rational(1,2);  b = new rational(2,4);
  Console.WriteLine(a.equals(b));
  a.multx(b);
  b = a.mult(b);
  Console.WriteLine(a);
  Console.WriteLine(b);
  a.Numerator = 3;   // not same as a.num = 3!!!
  a.Denominator = 0;
  Console.WriteLine(a.Numerator);
  Console.WriteLine(a.Denominator);
 } // Main
} // rats