Scala：如何对多个字母使用计数功能

Question

Ok so I'm trying to check the number of occurrences of a, b and c in a string and I'm trying to use a count function to do. Can I use that with multiple letters?

Answer 1

You can use scala Set

  val inSet = Set('a', 'b', 'c')
  "cat".count(inSet)

Scala Set has apply method with same behavior as contains , so when you do count(inSet) effectively you are doing count(c => inSet.apply(c)) which is equal to count(c => inSet.contains(c))

Answer 2

对于每个字符，只需检查此字符是否在您感兴趣的字符列表中，

"cat".count( ( c: Char ) => List( 'a', 'b', 'c').contains( c ) )