/* This file Fraction.java implements a class called Fraction.
 * Here we implement some simple operations commonly used with fractions,
 * namely adding, multiplying and reducing.  We also have a method that
 * enables us to print a fraction as a string like "17/20" with the slash.
 * There are many more things we could implement, such as handling
 * negative fractions, subtraction, division, reciprocal, mixed numerals,
 * and another constructor that creates a fraction out of a string as input.
 */
public class Fraction
{
  // Attributes:  numerator and denominator are both integers.
  private int num;
  private int denom;

  // Default Constructor:  just make it 1/1
  public Fraction()
  {
    num = 1;
    denom = 1;
  }

  // Initial value constructor:  initialize to a/b
  public Fraction(int a, int b)
  {
    num = a;
    denom = b;
  }

  // Copy constructor:  copy num and denom from existing fraction f.
  public Fraction(Fraction other)
  {
    num = other.num;
    denom = other.denom;
  }

  // Operations

  // toString() allows us to print fractions in the driver.
  public String toString()
  {
    return num + "/" + denom;
  }

  // To add fractions, we use the basic formula a/b + c/d = (ad+bc)/bd
  // But the important thing to notice here is the use of the word "this"
  // which refers to the fraction object before the . in the function call.
  // "this" is generally called the receiver object or implicit parameter.
  public Fraction add(Fraction other)
  {
    Fraction sum = new Fraction();
    sum.num = this.num * other.denom + this.denom * other.num;
    sum.denom = this.denom * other.denom;
    return sum;
  }

  // Multiplying fractions is easier than adding them.
  public Fraction multiply(Fraction other)
  {
    Fraction product = new Fraction();
    product.num = this.num * other.num;
    product.denom = this.denom * other.denom;
    return product;
  }

  // Someday, we should implement a "reduceMe()" function.
}