Negative base numbers: Difference between revisions

=={{header|Scala}}==

<lang scala>object NegativeBase {

val digits = ('0' to '9') ++ ('a' to 'z') ++ ('A' to 'Z')

def intToStr(n: Int, b: Int): String = {

def _fromInt(n: Int): List[Int] = {

if (n == 0) {

Nil

} else {

val r = n % b

val rp = if (r < 0) r + b else r

val m = -(n - rp)/b

rp :: _fromInt(m)

}

}

_fromInt(n).map(digits).reverse.mkString

}

def strToInt(s: String, b: Int): Int = {

s.map(digits.indexOf).foldRight((0, 1)){ case (x, (sum, pow)) =>

(sum + x * pow, pow * -b)

}._1

}

}</lang>

<lang scala>def testConversion(b: Int)(n: Int, s: String): Unit = {

println(s"$n in base -$b = ${NegativeBase.intToStr(n, b)}")

println(s"$s from base -$b = ${NegativeBase.strToInt(s, b)}")

}

testConversion(2)(10, "11110")

testConversion(3)(146, "21102")

testConversion(10)(15, "195")

testConversion(62)(795099356, "Scala")</lang>

{{out}}

<pre>10 in base -2 = 11110

11110 from base -2 = 10

146 in base -3 = 21102

21102 from base -3 = 146

15 in base -10 = 195

195 from base -10 = 15

795099356 in base -62 = Scala

Scala from base -62 = 795099356</pre>