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object Rationals {
// primary constuctor
class Rational(x :Int, y: Int) {
require(y != 0, "denominator must be non zero") // throws IllegalArgumentException
assert(y != 0) // throws AssertionError
// another constructor
def this(x: Int) = this(x, 1)
private def gcd(a: Int, b: Int): Int = if (b == 0) a else gcd(b, a % b)
private val g = gcd(x, y)
def numer = x / g
def denom = y / g
def neg = new Rational(-numer, denom)
def less(that: Rational) = this.numer * that.denom < that.numer * this.denom
def max(that: Rational) = if (this.less(that)) that else this
def add(that: Rational) =
new Rational(
numer * that.denom + that.numer * denom,
denom * that.denom)
def sub(that: Rational) = add(that.neg)
override def toString = numer + "/" + denom
}
def run = {
println("Rationals")
println(new Rational(2, 3).add(new Rational(3, 4)).toString)
println(new Rational(1, 3).sub(new Rational(5 ,7)).sub(new Rational(3, 2)).toString)
println(new Rational(1, 3).max(new Rational(5 ,7)).toString)
}
}
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