Scala编程之分数的四则运算

       在前面一篇关于Scala编程的文章中简单的介绍了Scala语言，关于Scala语言的一些语法及规则，如有感兴趣的朋友可以自己阅读相关书籍，鄙人诚挚推荐《Scala In Programming》，下面利用Scala语言实现简单的分数四则运算。

      1、分数的四则运算类

class Rational(n: Int,d: Int) {
//分母不能为0的校验
require(d != 0)

//分数的最简形式
private val simple = gcb(n.abs,d.abs)
val numer = n / simple
val denom = d / simple

//从构造器（分母为1）
def this(n: Int) = this(n,1)

//加
def +(that: Rational) : Rational = new Rational(
numer * that.denom + that.numer * denom,
denom * that.denom
)
def +(i: Int) : Rational = new Rational(
numer + i * denom,
denom
)

//减
def -(that: Rational) : Rational = new Rational(
numer * that.denom - that.numer * denom,
denom * that.denom
)
def -(i: Int) : Rational = new Rational(
numer - i * denom,
denom
)

//乘
def *(that : Rational) : Rational = new Rational(
numer * that.numer,
denom * that.denom
)
def *(i: Int) : Rational = new Rational(
numer * i,
denom
)

//除
def /(that: Rational) : Rational = new Rational(
numer * that.denom,
denom * that.numer
)
def /(i: Int) : Rational = new Rational(
numer,
denom * i
)

private def gcb(a:Int,b:Int) : Int = {
if(b == 0) a else gcb(b,a%b)
}

override def toString = numer + "/" + denom
}

      2、测试用例

object RationalDemo extends App{
val oneHalf = new Rational(1,2)
val twoHalf = new Rational(3,4)
val sum = oneHalf + twoHalf
val sub = oneHalf - twoHalf
val mul = oneHalf * twoHalf
val div = oneHalf / twoHalf
println("oneHalf + twoHalf = " + sum)
println("oneHalf - twoHalf = " + sub)
println("oneHalf * twoHalf = " + mul)
println("oneHalf / twoHalf = " + div)
}

       3、测试结果

      oneHalf + twoHalf = 5/4

      oneHalf - twoHalf = -1/4

      oneHalf * twoHalf = 3/8

      oneHalf / twoHalf = 2/3