Coursera Scala 2-5,6：类
class Rational(n: Int, d: Int) {
require(d != 0)
private val g = gcd(n.abs, d.abs)
//将构造器传入的参数，赋值成成员变量，外部才可以访问
val numer = n / g
val denom = d / g
def this(n: Int) = this(n, 1)
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)
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)
def *(that: Rational): Rational =
new Rational(numer * that.numer, denom * that.denom)
def *(i: Int): Rational =
new Rational(numer * i, denom)
def /(that: Rational): Rational =
new Rational(numer * that.denom, denom * that.numer)
def /(i: Int): Rational =
new Rational(numer, denom * i)
//override关键字重载函数
override def toString = numer+"/"+denom
private def gcd(a: Int, b: Int): Int =
if (b == 0) a else gcd(b, a % b)
}
富操作/中缀表达式
scala允许函数用如下表示：
| 富操作 | 原表示方法 |
|---|---|
| r add s | r.add(s) |
| r less s | r.less(s) |
优先级
scala中符号优先级，逐次增高
|
^
&
<>
= ！
：
+ -
* / %
参考here
