如何在scala的范围内进行模式匹配?

内部模式匹配可以用防护装置表示:

n match {
  case it if 0 until 5 contains it  => "less than five"
  case it if 5 until 10 contains it => "less than ten"
  case _ => "a lot"
}

class Contains(r: Range) { def unapply(i: Int): Boolean = r contains i }

val C1 = new Contains(3 to 10)
val C2 = new Contains(20 to 30)

scala> 5 match { case C1() => println("C1"); case C2() => println("C2"); case _ => println("none") }
C1

scala> 23 match { case C1() => println("C1"); case C2() => println("C2"); case _ => println("none") }
C2

scala> 45 match { case C1() => println("C1"); case C2() => println("C2"); case _ => println("none") }
none

请注意,包含实例的名称应使用初始大写字母。如果你不这样做,你需要在后面的引号中加上这个名字(这里很难,除非我不知道有一个转义)

类似于@yardena的答案,但使用基本比较:

n match {
    case i if (i >= 0 && i < 5) => "less than five"
    case i if (i >= 5 && i < 10) => "less than ten"
    case _ => "a lot"
}

也适用于浮点N

对于相同大小的范围,可以使用旧的学校数学:

val a = 11 
(a/10) match {                      
    case 0 => println (a + " in 0-9")  
    case 1 => println (a + " in 10-19") } 

11 in 10-19

是的,我知道:“没有必要就不要分裂!” 但是:分而治之!