Black monkey house: Scala guard

Like for expression, like, match function is also provided guards, guards can be any Boolean conditions
match guarding function

for(i <- "+-*/3"){
  var sn = 0
  var dit = 0
  i match{
    case '+' => sn = 1
    case '-' => sn = 2
    //守卫模式
    case _ if i.toString.equals("3") => sn = 5; dit = 4
    case _ => sn = 6
  }
  println(i + " " + sn + " " + dit)
}

Reproduced in: https: //www.jianshu.com/p/bcbcd4b62eeb