Scala: Shift elements in an Array

Question

I'm getting used to the various data structures in Scala and I've noticed that this function (contrived example), which is supposed to move every character in the mutable array to the right by one, has no effect on the array:

  def shiftRight(str: String): Array[Char] = {
    val chars = str.toCharArray
    for(i <- chars.length - 1 until 0) chars(i) = chars(i - 1)
    chars
  }
  println(shiftRight("ABCD").mkString)

which produces the result

ABCD

not the expected

AABC

Or even better to use more explicit i <- Range(start = chars.length - 1, end = 0, step = -1) — sarveshseri
– sarveshseri, Commented Dec 26, 2016 at 15:12

insan-e · Accepted Answer · 2016-12-26 15:07:46Z

5

Default step for range is one. See class Range here and implicit that gets you to it here.
Instead of

for(i <- chars.length - 1 until 0)...

you need:

for(i <- chars.length - 1 until 0 by -1)...

answered Dec 26, 2016 at 15:07

insan-e

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