Negative base numbers

From Rosetta Code
Task
Negative base numbers
You are encouraged to solve this task according to the task description, using any language you may know.

Negative base numbers are an alternate way to encode numbers without the need for a minus sign. Various negative bases may be used including negadecimal (base -10), negabinary (-2) and negaternary (-3).[1][2]


Task
  • Encode the decimal number 10 as negabinary (expect 11110)
  • Encode the decimal number 146 as negaternary (expect 21102)
  • Encode the decimal number 15 as negadecimal (expect 195)
  • In each of the above cases, convert the encoded number back to decimal.


extra credit
  • supply an integer, that when encoded to base   -62   (or something "higher"),   expresses the
    name of the language being used   (with correct capitalization).   If the computer language has
    non-alphanumeric characters,   try to encode them into the negatory numerals,   or use other
    characters instead.



ALGOL 68

Works with: ALGOL 68G version Any - tested with release 2.8.3.win32

<lang algol68># Conversion to/from negative base numbers #

  1. Note - no checks for valid bases or digits bases -2 .. -63 are handled #
  2. A-Z represent the digits 11 .. 35, a-z represent the digits 36 .. 61 #
  3. the digit 62 is represented by a space #
  1. 1 2 3 4 5 6 #
  2. 01234567890123456789012345678901234567890123456789012 #

[]CHAR base digits = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz "[ AT 0 ];

  1. returns s decoded to an integer from the negative base b #

PRIO FROMNBASE = 9; OP FROMNBASE = ( STRING s, INT b )LONG INT: 

    BEGIN
       LONG INT    result          := 0;
       LONG INT    base multiplier := 1;
       FOR d pos FROM UPB s BY -1 TO LWB s DO
           INT digit = IF   s[ d pos ] = " "
                       THEN 62
                       ELIF s[ d pos ] >= "a"
                       THEN ( ABS s[ d pos ] + 36 ) - ABS "a"
                       ELIF s[ d pos ] >= "A"
                       THEN ( ABS s[ d pos ] + 10 ) - ABS "A"
                       ELSE ABS s[ d pos ] - ABS "0"
                       FI;
           result          +:= base multiplier * digit;
           base multiplier *:= b
       OD;
       result
    END # FROMNBASE # ;

OP FROMNBASE = ( CHAR c, INT b )LONG INT: STRING(c) FROMNBASE b;

  1. returns n encoded as a string in the negative base b #

PRIO TONBASE = 9; OP TONBASE = ( LONG INT n, INT b )STRING: 

    BEGIN
       STRING   result := "";
       LONG INT v      := n;
       WHILE
           INT d := SHORTEN IF v < 0 THEN - ( ABS v MOD b ) ELSE v MOD b FI;
           v OVERAB b;
           IF d < 0
           THEN
               d -:= b;
               v +:= 1
           FI;
           base digits[ d ] +=: result;
           v /= 0
       DO SKIP OD;
       result
    END # TONBASE # ;
  1. tests the TONBASE and FROMNBASE operators #

PROC test n base = ( LONG INT number, INT base, STRING expected )VOID: 

    BEGIN
       PROC expect = ( BOOL result )STRING: IF result THEN "" ELSE " INCORRECT" FI;
       STRING   encoded = number  TONBASE   base;
       LONG INT decoded = encoded FROMNBASE base;
       print( ( whole( number, 0 ), " encodes to: ", encoded ) );
       print( ( " base ", whole( base, 0 ), expect( encoded = expected ), newline ) );
       print( ( encoded, " decodes to: ", whole( decoded, 0 ) ) );
       print( ( " base ", whole( base, 0 ), expect( decoded = number   ), newline ) )
    END # test n base # ;

test n base( 10, -2, "11110" ); test n base( 146, -3, "21102" ); test n base( 15, -10, "195" );

  1. The defining document for ALGOL 68 spells the name "Algol 68" on the cover, though inside it is "ALGOL 68" #
  2. at the risk of "judging a language by it's cover", we use "Algol 68" as the name here... #

test n base( - LONG 36492107981104, -63, "Algol 68" )</lang>

Output:
10 encodes to: 11110 base -2
11110 decodes to: 10 base -2
146 encodes to: 21102 base -3
21102 decodes to: 146 base -3
15 encodes to: 195 base -10
195 decodes to: 15 base -10
-36492107981104 encodes to: Algol 68 base -63
Algol 68 decodes to: -36492107981104 base -63

C#

Translation of: Java

<lang csharp>using System; using System.Collections.Generic; using System.Linq; using System.Text;

namespace NegativeBaseNumbers { 

   class Program {
       const string DIGITS = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";

       static string EncodeNegativeBase(long n, int b) {
           if (b < -62 || b > -1) {
               throw new ArgumentOutOfRangeException("b");
           }
           if (n == 0) {
               return "0";
           }
           StringBuilder output = new StringBuilder();
           long nn = n;
           while (nn != 0) {
               int rem = (int)(nn % b);
               nn /= b;
               if (rem < 0) {
                   nn++;
                   rem -= b;
               }
               output.Append(DIGITS[rem]);
           }
           return new string(output.ToString().Reverse().ToArray());
       }

       static long DecodeNegativeBase(string ns, int b) {
           if (b < -62 || b > -1) {
               throw new ArgumentOutOfRangeException("b");
           }
           if (ns == "0") {
               return 0;
           }
           long total = 0;
           long bb = 1;
           for (int i = ns.Length - 1; i >= 0; i--) {
               char c = ns[i];
               total += DIGITS.IndexOf(c) * bb;
               bb *= b;
           }
           return total;
       }

       static void Main(string[] args) {
           List<Tuple<long, int>> nbl = new List<Tuple<long, int>>() {
               new Tuple<long, int>(10,-2),
               new Tuple<long, int>(146,-3),
               new Tuple<long, int>(15,-10),
               new Tuple<long, int>(-34025238427,-62),
           };
           foreach (var p in nbl) {
               string ns = EncodeNegativeBase(p.Item1, p.Item2);
               Console.WriteLine("{0,12} encoded in base {1,-3} = {2}", p.Item1, p.Item2, ns);
               long n = DecodeNegativeBase(ns, p.Item2);
               Console.WriteLine("{0,12} decoded in base {1,-3} = {2}", ns, p.Item2, n);
               Console.WriteLine();
           }
       }
   }

}</lang>

Output:
          10 encoded in base -2  = 11110
       11110 decoded in base -2  = 10

         146 encoded in base -3  = 21102
       21102 decoded in base -3  = 146

          15 encoded in base -10 = 195
         195 decoded in base -10 = 15

-34025238427 encoded in base -62 = csharp
      csharp decoded in base -62 = -34025238427

D

<lang D>import std.stdio;

immutable DIGITS = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";

void main() { 

   driver(10, -2);
   driver(146, -3);
   driver(15, -10);
   driver(13, -62);

}

void driver(long n, int b) { 

   string ns = encodeNegBase(n, b);
   writefln("%12d encoded in base %3d = %12s", n, b, ns);

   long p = decodeNegBase(ns, b);
   writefln("%12s decoded in base %3d = %12d", ns, b, p);

   writeln;

}

string encodeNegBase(long n, int b) in { 

   import std.exception : enforce;
   enforce(b <= -1 && b >= -62);

} body { 

   if (n==0) return "0";
   char[] output;
   long nn = n;
   while (nn != 0) {
       int rem = nn % b;
       nn /= b;
       if (rem < 0) {
           nn++;
           rem -= b;
       }
       output ~= DIGITS[rem];
   }

   import std.algorithm : reverse;

   reverse(output);
   return cast(string) output;

}

long decodeNegBase(string ns, int b) in { 

   import std.exception : enforce;
   enforce(b <= -1 && b >= -62);

} body { 

   if (ns == "0") return 0;
   long total = 0;
   long bb = 1;
   foreach_reverse (c; ns) {
       foreach(i,d; DIGITS) {
           if (c==d) {
               total += i * bb;
               bb *= b;
               break;
           }
       }
   }
   return total;

}</lang>

Output:
          10 encoded in base  -2 =        11110
       11110 decoded in base  -2 =           10

         146 encoded in base  -3 =        21102
       21102 decoded in base  -3 =          146

          15 encoded in base -10 =          195
         195 decoded in base -10 =           15

          13 encoded in base -62 =            D
           D decoded in base -62 =           13

Go

Translation of: Kotlin

<lang go>package main

import ( 

   "fmt"
   "log"
   "strings"

)

const digits = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"

func reverse(bs []byte) []byte { 

   for i, j := 0, len(bs)-1; i < len(bs)/2; i, j = i+1, j-1 {
       bs[i], bs[j] = bs[j], bs[i]
   }
   return bs

}

func encodeNegBase(n, b int64) (string, error) { 

   if b < -62 || b > -1 {
       return "", fmt.Errorf("base must be between -62 and -1 inclusive")
   }
   if n == 0 {
       return "0", nil
   }
   var out []byte
   for n != 0 {
       rem := n % b
       n /= b
       if rem < 0 {
           n++
           rem -= b
       }
       out = append(out, digits[int(rem)])
   }
   reverse(out)
   return string(out), nil

}

func decodeNegBase(ns string, b int64) (int64, error) { 

   if b < -62 || b > -1 {
       return 0, fmt.Errorf("base must be between -62 and -1 inclusive")
   }
   if ns == "0" {
       return 0, nil
   }
   total := int64(0)
   bb := int64(1)
   bs := []byte(ns)
   reverse(bs)
   for _, c := range bs {
       total += int64(strings.IndexByte(digits, c)) * bb
       bb *= b
   }
   return total, nil

}

func main() { 

   numbers := []int64{10, 146, 15, -942, 1488588316238}
   bases := []int64{-2, -3, -10, -62, -62}
   for i := 0; i < len(numbers); i++ {
       n := numbers[i]
       b := bases[i]
       ns, err := encodeNegBase(n, b)
       if err != nil {
           log.Fatal(err)
       }
       fmt.Printf("%13d encoded in base %-3d = %s\n", n, b, ns)
       n, err = decodeNegBase(ns, b)
       if err != nil {
           log.Fatal(err)
       }
       fmt.Printf("%13s decoded in base %-3d = %d\n\n", ns, b, n)
   }

}</lang>

Output:
           10 encoded in base -2  = 11110
        11110 decoded in base -2  = 10

          146 encoded in base -3  = 21102
        21102 decoded in base -3  = 146

           15 encoded in base -10 = 195
          195 decoded in base -10 = 15

         -942 encoded in base -62 = Go
           Go decoded in base -62 = -942

1488588316238 encoded in base -62 = Rosetta
      Rosetta decoded in base -62 = 1488588316238

Haskell

<lang haskell>import Data.Char (chr, ord) import Numeric (showIntAtBase)

-- The remainder and quotient of n/d, where the remainder is guaranteed to be -- non-negative. The divisor, d, is assumed to be negative. quotRemP :: Integral a => a -> a -> (a, a) quotRemP n d = let (q, r) = quotRem n d 

              in if r < 0 then (q+1, r-d) else (q, r)

-- Convert the number n to base b, where b is assumed to be less than zero. toNegBase :: Integral a => a -> a -> a toNegBase b n = let (q, r) = quotRemP n b 

               in if q == 0 then r else negate b * toNegBase b q + r

-- Convert n to a string, where n is assumed to be a base b number, with b less -- than zero. showAtBase :: (Integral a, Show a) => a -> a -> String showAtBase b n = showIntAtBase (abs b) charOf n "" 

 where charOf m | m < 10    = chr $ m + ord '0'
                | m < 36    = chr $ m + ord 'a' - 10
                | otherwise = '?'

-- Print a number in base b, where b is assumed to be less than zero. printAtBase :: (Integral a, Show a) => a -> a -> IO () printAtBase b = putStrLn . showAtBase b . toNegBase b

main :: IO () main = do 

 printAtBase (-2)  10
 printAtBase (-3)  146
 printAtBase (-10) 15
 printAtBase (-16) 107
 printAtBase (-36) 41371458</lang>
Output:
$ ./negbase 
11110
21102
195
1ab
perl6

J

The j languages has builtin base and antibase verbs defined over the full complex realm. However, antibase produces negative digits. Additional coding required for antibase. Negative base works as is once the literal is converted back to a base 10 vector.


Model: python version. Python and j divmod for negative divisor agree but for transposition. 

>>> # python divmod
>>> [divmod(i, -2) for i in (2, 3, 4, 5)]
[(-1, 0), (-2, -1), (-2, 0), (-3, -1)]
>>>

   NB. j divmod
   divmod =: <.@:%`(|~)`:0
   2 3 4 5 divmod _2
_1 _2 _2 _3
 0 _1  0 _1



NB. Use:  BASE encode_neg_base INTEGER
NB. Output: literal
neg_antibase =: dyad define
 b =. x
 n =. y
 if. 0 = n do. '0' return. end.
 out =. i.0
 while. n do.
  'n rem' =. n divmod b
  if. rem < 0 do.
   n =. >: n
   rem =. rem - b
  end.
  out =. out , rem
 end.
 (|. out) { _10 |. AlphaNum_j_
)

NB. use:  BASE neg_base LITERAL
NB. output: integer
neg_base =: #. (_10 |. AlphaNum_j_)&i.

   NB. neg_antibase test passes
   _2 _3 _10 neg_antibase&> 10 146 15
11110
21102
195  

   NB. in j we would write the tautology
   (":&.>11110 21102 195) -: _2 _3 _10 neg_antibase&.> 10 146 15
1
   

   NB. expressive numeric notation
   NB. we can write the numbers in arbitrary base
   NB. The digit characters are limited to [0-9a-z]

   _2b11110   _3b21102   _10b195
10 146 15


   NB. neg_base test passes

   _2 neg_base '11110'
10

   _3 neg_base '21102'
146
   
   _10 neg_base '195'
15


   [ EXTRA_CREDIT =: _63 neg_base&> ;: 'J j apl APL Iverson'
19 45 139718 38136 1069471233985
   
   _63 neg_antibase&> EXTRA_CREDIT
J      
j      
apl    
APL    
Iverson

=={{header|Java}}==
{{trans|Kotlin}}
{{works with|Java|9}}
<lang Java>import java.util.List;
import java.util.Map;
import java.util.Objects;

public class NegativeBaseNumbers {
    private static final String DIGITS = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";

    private static String encodeNegBase(long n, int b) {
        if (b < -62 || b > -1) throw new IllegalArgumentException("Parameter b is out of bounds");
        if (n == 0) return "0";
        StringBuilder out = new StringBuilder();
        long nn = n;
        while (nn != 0) {
            int rem = (int) (nn % b);
            nn /= b;
            if (rem < 0) {
                nn++;
                rem -= b;
            }
            out.append(DIGITS.charAt(rem));
        }
        out.reverse();
        return out.toString();
    }

    private static long decodeNegBase(String ns, int b) {
        if (b < -62 || b > -1) throw new IllegalArgumentException("Parameter b is out of bounds");
        if (Objects.equals(ns, "0")) return 0;
        long total = 0;
        long bb = 1;
        for (int i = ns.length() - 1; i >= 0; i--) {
            char c = ns.charAt(i);
            total += DIGITS.indexOf(c) * bb;
            bb *= b;
        }
        return total;
    }

    public static void main(String[] args) {
        List<Map.Entry<Long, Integer>> nbl = List.of(
                Map.entry(10L, -2),
                Map.entry(146L, -3),
                Map.entry(15L, -10),
                Map.entry(-4393346L, -62)
        );
        for (Map.Entry<Long, Integer> p : nbl) {
            String ns = encodeNegBase(p.getKey(), p.getValue());
            System.out.printf("%12d encoded in base %-3d = %s\n", p.getKey(), p.getValue(), ns);
            long n = decodeNegBase(ns, p.getValue());
            System.out.printf("%12s decoded in base %-3d = %d\n\n", ns, p.getValue(), n);
        }
    }
}</lang>
{{out}}
<pre>          10 encoded in base -2  = 11110
       11110 decoded in base -2  = 10

         146 encoded in base -3  = 21102
       21102 decoded in base -3  = 146

          15 encoded in base -10 = 195
         195 decoded in base -10 = 15

    -4393346 encoded in base -62 = Java
        Java decoded in base -62 = -4393346

jq

Works with: jq version 1.5

If your jq does not have `trunc/0` then use this: <lang jq>def trunc: if . >= 0 then floor else -(-(.)|trunc) end;</lang> <lang jq>def negbase($b): 

 if ($b >= 0) then error("negbase requires negative base")
 elif . == 0 then "0"
 else {n: ., ans: ""}
 | until(.n == 0;
        .r = ((.n % $b))
 	 | .n = ((.n / $b) | trunc)
        | if .r < 0 then .n += 1 | .r -= $b else . end
        | .ans = (.r|tostring) + .ans )
 | .ans
 end ;

def sigma(stream): reduce stream as $x (null; .+$x);

def invnegbase($b): 

 (explode | reverse | map(. - 48)) as $s
 | sigma( range(0; $s|length) | ($s[.] * pow($b; .)));

def testset: { 

  "11110": [10, -2],
  "21102": [146, -3],
  "195":   [15, -10]
};

def test: testset | to_entries[] | .value[0] as $n | .value[1] as $base | ($n|negbase($base)) as $neg | ($neg | invnegbase($base)) as $invneg | [.key == $neg, $n == $invneg]

test</lang>

Output:

<lang jq>[true,true] [true,true] [true,true]</lang>

Julia

Works with: Julia version 0.6

<lang julia> function negbase(n, b) 

   if n == 0 return "0" end
   out = IOBuffer()
   while n != 0
       n, r = divrem(n, b)
       if r < 0
           n += 1
           r -= b
       end
       print(out, r)
   end
   return reverse(String(out))

end

invnegbase(nst, b) = sum((ch - '0') * b ^ (i - 1) for (i, ch) in enumerate(reverse(nst)))

testset = Dict( 

   (10, -2) => "11110",
   (143, -3) => "21102",
   (15, -10) => "195")

for ((num, base), rst) in testset 

   encoded = negbase(num, base)
   decoded = invnegbase(encoded, base)
   println("\nencode $num in base $base:\n-> expected: $rst\n-> resulted: $encoded\n-> decoded: $decoded")

end</lang>

Output:
encode 10 in base -2:
-> expected: 11110
-> resulted: 11110
-> decoded: 10

encode 15 in base -10:
-> expected: 195
-> resulted: 195
-> decoded: 15

encode 143 in base -3:
-> expected: 21102
-> resulted: 21112
-> decoded: 143

Kotlin

<lang scala>// version 1.1.2

const val DIGITS = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"

fun encodeNegBase(n: Long, b: Int): String { 

   require(b in -62 .. -1)
   if (n == 0L) return "0"
   val out = mutableListOf<Char>()
   var nn = n
   while (nn != 0L) {
       var rem = (nn % b).toInt()
       nn /= b
       if (rem < 0) {
           nn++
           rem -= b
       }
       out.add(DIGITS[rem])
   }
   out.reverse()
   return out.joinToString("")

}

fun decodeNegBase(ns: String, b: Int): Long { 

   require(b in -62 .. -1)
   if (ns == "0") return 0
   var total = 0L
   var bb = 1L
   for (c in ns.reversed()) {
       total += DIGITS.indexOf(c) * bb
       bb *= b
   }
   return total

}

fun main(args:Array<String>) { 

   val nbl = listOf(10L to -2, 146L to -3, 15L to -10, -17596769891 to -62)
   for (p in nbl) {
       val ns = encodeNegBase(p.first, p.second)
       System.out.printf("%12d encoded in base %-3d = %s\n", p.first, p.second, ns)
       val n  = decodeNegBase(ns, p.second)
       System.out.printf("%12s decoded in base %-3d = %d\n\n", ns, p.second, n)
   }

}</lang>

Output:
          10 encoded in base -2  = 11110
       11110 decoded in base -2  = 10

         146 encoded in base -3  = 21102
       21102 decoded in base -3  = 146

          15 encoded in base -10 = 195
         195 decoded in base -10 = 15

-17596769891 encoded in base -62 = Kotlin
      Kotlin decoded in base -62 = -17596769891

Mathematica

<lang Mathematica>EncodeBase[number_,base_]:=Module[{ 

 out={},
 rem,n=number,b=base
},
While[
 n!=0,
 {n,rem}={Floor[Divide[n,b]],Mod[n,b]};
 If[
  rem<0,
  n+=1;
  rem-=b
 ];
 PrependTo[out,rem]
];
out

]; DecodeBase[list_,base_]:=Total[list*base^Range[Length[list]-1,0,-1]];

Print[EncodeNegBase[10,-2],"=",DecodeBase[EncodeNegBase[10,-2],-2]]; Print[EncodeNegBase[146,-3],"=",DecodeBase[EncodeNegBase[146,-3],-3]]; Print[EncodeNegBase[15,-10],"=",DecodeBase[EncodeNegBase[15,-10],-10]];</lang> 

{1,1,1,1,0}=10
{2,1,1,0,2}=146
{1,9,5}=15

Extra Credit: <lang Mathematica>DecodeBase[ToCharacterCode[$Version], -126](*ascii 1-byte encoding*) DecodeBase[ToCharacterCode[$Version], -(2^16 - 1)](*2-byte encoding*)</lang> 

805433247971592164648901981307140864173502418954511864100981464890629926293823767730118860531000284192172723837
1402171866107096793294662824351970913227448502019658754262020315290937172496459102043149157175108006798078612200544768242812932737034448604720533372980987964929785521161173764118702296122915325508945150191589743829011670147956776269027485433441427722106

Modula-2

<lang modula2>MODULE NegativeBase; FROM FormatString IMPORT FormatString; FROM Terminal IMPORT WriteString,WriteLn,ReadChar;

CONST DIGITS = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"; TYPE String = ARRAY[0..63] OF CHAR;

PROCEDURE EncodeNegativeBase(n : LONGINT; base : LONGINT) : String; 

   PROCEDURE Mod(a,b : LONGINT) : LONGINT;
   BEGIN
       RETURN a - (a / b) * b
   END Mod;

   PROCEDURE Swap(VAR a,b : CHAR);
   VAR t : CHAR;
   BEGIN
       t := a;
       a := b;
       b := t
   END Swap;

VAR 

   ptr,idx : CARDINAL;
   rem : LONGINT;
   result : String;

BEGIN 

   IF (base > -1) OR (base < -62) THEN
       RETURN result
   ELSIF n = 0 THEN
       result := "0"
   ELSE
       ptr := 0;
       WHILE n # 0 DO
           rem := Mod(n, base);
           n := n / base;
           IF rem < 0 THEN
               INC(n);
               rem := rem - base
           END;
           result[ptr] := DIGITS[rem];
           INC(ptr);
       END
   END;
   result[ptr] := 0C;

   idx := 0;
   DEC(ptr);
   WHILE idx < ptr DO
       Swap(result[idx], result[ptr]);
       INC(idx);
       DEC(ptr)
   END;

   RETURN result

END EncodeNegativeBase;

PROCEDURE DecodeNegativeBase(ns : String; base : LONGINT) : LONGINT; VAR 

   total,bb,i,j : LONGINT;

BEGIN 

   IF (base < -62) OR (base > -1) THEN
       RETURN 0
   ELSIF (ns[0] = 0C) OR ((ns[0] = '0') AND (ns[1] = 0C)) THEN
       RETURN 0
   ELSE
       FOR i:=0 TO HIGH(ns) DO
           IF ns[i] = 0C THEN
               BREAK
           END
       END;
       DEC(i);

       total := 0;
       bb := 1;
       WHILE i >= 0 DO
           FOR j:=0 TO HIGH(DIGITS) DO
               IF ns[i] = DIGITS[j] THEN
                   total := total + j * bb;
                   bb := bb * base;
                   BREAK
               END
           END;
           DEC(i)
       END;
   END;
   RETURN total

END DecodeNegativeBase;

PROCEDURE Driver(n,b : LONGINT); VAR 

   ns,buf : String;
   p : LONGINT;

BEGIN 

   ns := EncodeNegativeBase(n, b);
   FormatString("%12l encoded in base %3l = %12s\n", buf, n, b, ns);
   WriteString(buf);

   p := DecodeNegativeBase(ns, b);
   FormatString("%12s decoded in base %3l = %12l\n", buf, ns, b, p);
   WriteString(buf);

   WriteLn

END Driver;

BEGIN 

   Driver(10, -2);
   Driver(146, -3);
   Driver(15, -10);
   Driver(-19425187910, -62);

   ReadChar

END NegativeBase.</lang>

Output:
          10 encoded in base  -2 =        11110
       11110 decoded in base  -2 =           10

         146 encoded in base  -3 =        21102
       21102 decoded in base  -3 =          146

          15 encoded in base -10 =          195
         195 decoded in base -10 =           15

-19425187910 encoded in base -62 =       Modula
      Modula decoded in base -62 = -19425187910

ooRexx

Translation of: REXX

<lang oorexx>/* REXX ---------------------------------------------------------------

  • Adapt for ooRexx (use of now invalid variable names)
  • and make it work for base -63 (Algol example)
  • --------------------------------------------------------------------*/

Numeric Digits 20 digits='0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz ' txt=' converted to base ' n= 10; b= -2; nb=nBase(n,b); Say right(n,20) txt right(b,3) '---->' nb ok() n= 146; b= -3; nb=nBase(n,b); Say right(n,20) txt right(b,3) '---->' nb ok() n= 15; b=-10; nb=nBase(n,b); Say right(n,20) txt right(b,3) '---->' nb ok() n= -15; b=-10; nb=nBase(n,b); Say right(n,20) txt right(b,3) '---->' nb ok() n= 0; b= -5; nb=nBase(n,b); Say right(n,20) txt right(b,3) '---->' nb ok() n=-6284695; b=-62; nb=nBase(n,b); Say right(n,20) txt right(b,3) '---->' nb ok() n=-36492107981104; b=-63;nb=nBase(n,b); Say right(n,20) txt right(b,3) '---->' nb ok() Exit

nBase: Procedure Expose digits /*---------------------------------------------------------------------

  • convert x (base 10) to result (base r)
  • --------------------------------------------------------------------*/
 Parse arg x,r
 result=
 Do While x\==0              /*keep Processing while  X  isn't zero.*/
   z=x//r
   x=x%r                     /*calculate remainder; calculate int ÷.*/
   If z<0 Then Do
     z=z-r                   /*subtract a negative  R  from  Z ?--+ */
     x=x+1                   /*bump  X  by one.                   ¦ */
     End
   result=substr(digits,z+1,1)result        /*prepend the new digit */
   End
 If result= Then result=0
 Return result

pBase: Procedure Expose digits; /*---------------------------------------------------------------------

  • convert x (base r) to result (base 10)
  • --------------------------------------------------------------------*/
 Parse arg x,r;
 result=0;
 p=0
 len=length(x)
 Do j=len by -1 For len            /*Process each of the X's digits */
   v=pos(substr(x,j,1),digits)-1   /*use digit's numeric value.     */
   result=result+v*r**p;           /*add it to result               */
   p=p+1                           /*bump power by 1                */
   End
 Return result

ok: /*---------------------------------------------------------------------

  • check back conversion
  • --------------------------------------------------------------------*/
 back=pBase(nb,b)
 If back\=n  Then
   r='Error backward conversion results in' back
 Else
   r='ok'
 Return r</lang>
Output:
                  10  converted to base   -2 ----> 11110 ok
                 146  converted to base   -3 ----> 21102 ok
                  15  converted to base  -10 ----> 195 ok
                 -15  converted to base  -10 ----> 25 ok
                   0  converted to base   -5 ----> 0 ok
            -6284695  converted to base  -62 ----> Rexx ok
     -36492107981104  converted to base  -63 ----> Algol 68 ok

Perl 6

Works with: Rakudo version 2016.11

Perl 6 provides built-in methods / routines base and parse-base to convert to and from bases 2 through 36. We'll just shadow the core routines with versions that accept negative bases.

As a stretch goal, rather than implement something that can "Spell the name of the language with correct capitalization" (which is silly, trivial, and has absolutely nothing to do with negative base numbers,) we'll implement routines that correctly work with any Real number, not just integers.

The Real candidate has a 'precision' parameter, default -15, (15 places after the decimal point,) to limit the length of the fractional portion of the converted value. Change it if you need or want different precision. The Integer only routine is kept here as a multi-dispatch candidate since it is potentially much faster than the Real capable routine. The dispatcher will automatically use the most appropriate (fastest) routine.

Note that the parse-base routine will handle 'illegal' negative negative-base values without blowing up.

<lang perl6>multi sub base ( Int $value is copy, Int $radix where -37 < * < -1) { 

   my $result;
   while $value {
       my $r = $value mod $radix;
       $value div= $radix;
       if $r < 0 {
           $value++;
           $r -= $radix
       }
       $result ~= $r.base(-$radix);
   }
   flip $result || ~0;

}

multi sub base ( Real $num, Int $radix where -37 < * < -1, :$precision = -15 ) { 

   return '0' unless $num;
   my $value  = $num;
   my $result = ;
   my $place  = 0;
   my $upper-bound = 1 / (-$radix + 1);
   my $lower-bound = $radix * $upper-bound;

   $value = $num / $radix ** ++$place until $lower-bound <= $value < $upper-bound;

   while ($value or $place > 0) and $place > $precision {
       my $digit = ($radix * $value - $lower-bound).Int;
       $value    =  $radix * $value - $digit;
       $result ~= '.' unless $place or $result.contains: '.';
       $result ~= $digit == -$radix ?? ($digit-1).base(-$radix)~'0' !! $digit.base(-$radix);
       $place--
   }
   $result

}

multi sub parse-base (Str $str, Int $radix where -37 < * < -1) { 

   return -1 * $str.substr(1).&parse-base($radix) if $str.substr(0,1) eq '-';
   my ($whole, $frac) = $str.split: '.';
   my $fraction = 0;
   $fraction = [+] $frac.comb.kv.map: { $^v.parse-base(-$radix) * $radix ** -($^k+1) } if $frac;
   $fraction + [+] $whole.flip.comb.kv.map: { $^v.parse-base(-$radix) * $radix ** $^k }

}

  1. TESTING

for <4 -4 0 -7 10 -2 146 -3 15 -10 -19 -10 107 -16 

   227.65625 -16  2.375 -4 -1.3e2 -8 41371457.268272761 -36> -> $v, $r {
   my $nbase = $v.&base($r, :precision(-5));
   printf "%20s.&base\(%3d\) = %-11s : %13s.&parse-base\(%3d\) = %s\n",
     $v, $r, $nbase, "'$nbase'", $r, $nbase.&parse-base($r);

}

  1. 'Illegal' negative-base value

say q| '-21'.&parse-base(-10) = |, '-21'.&parse-base(-10);</lang>

Output:
                   4.&base( -4) = 130         :         '130'.&parse-base( -4) = 4
                   0.&base( -7) = 0           :           '0'.&parse-base( -7) = 0
                  10.&base( -2) = 11110       :       '11110'.&parse-base( -2) = 10
                 146.&base( -3) = 21102       :       '21102'.&parse-base( -3) = 146
                  15.&base(-10) = 195         :         '195'.&parse-base(-10) = 15
                 -19.&base(-10) = 21          :          '21'.&parse-base(-10) = -19
                 107.&base(-16) = 1AB         :         '1AB'.&parse-base(-16) = 107
           227.65625.&base(-16) = 124.68      :      '124.68'.&parse-base(-16) = 227.65625
               2.375.&base( -4) = 3.32        :        '3.32'.&parse-base( -4) = 2.375
              -1.3e2.&base( -8) = 1616        :        '1616'.&parse-base( -8) = -130
  41371457.268272761.&base(-36) = PERL6.ROCKS : 'PERL6.ROCKS'.&parse-base(-36) = 41371457.268272761
  '-21'.&parse-base(-10) = 19

Phix

<lang Phix>constant digits = "0123456789"& 

                 "ABCDEFGHIJKLMNOPQRSTUVWXYZ"&
                 "abcdefghijklmnopqrstuvwxyz"

type base(integer b) 

   return b<=-1 and b>=-length(digits)

end type

function encodeNegBase(atom n, base b) 

   string res = iff(n?"":"0")
   while n!=0 do
       atom r = remainder(n,b)
       n = trunc(n/b)
       if r<0 then
           n += 1
           r -= b
       end if
       res &= digits[r+1]
   end while
   return reverse(res)

end function

function decodeNegBase(string ns, base b) 

   atom total = 0,
        bb = 1
   for i=length(ns) to 1 by -1 do
       integer k = find(ns[i],digits)-1
       if k=-1 or k>-b then return "invalid digit" end if
       total += k*bb
       bb *= b
   end for
   return total

end function 

               -- decimal, base, expected

constant tests = {{10, -2, "11110"}, 

                 {146,     -3,   "21102"},
                 {15,      -10,  "195"},
                 {-5795577,-62,  "Phix"}}

procedure main() atom n,b string e 

   for i=1 to length(tests) do
       {n,b,e} = tests[i]
       string ns = encodeNegBase(n, b)
       printf(1,"%9d in base %-3d is %6s\n", {n, b, ns})
       atom nn = decodeNegBase(ns, b)
       string ok = iff(ns=e and nn=n?""," ????")
       printf(1,"%9d <--------------'%s\n",{nn,ok})
   end for

end procedure main()</lang>

Output:
       10 in base -2  is  11110
       10 <--------------'
      146 in base -3  is  21102
      146 <--------------'
       15 in base -10 is    195
       15 <--------------'
 -5795577 in base -62 is   Phix
 -5795577 <--------------'

Python

<lang python>#!/bin/python from __future__ import print_function

def EncodeNegBase(n, b): #Converts from decimal if n == 0: return "0" out = [] while n != 0: n, rem = divmod(n, b) if rem < 0: n += 1 rem -= b out.append(rem) return "".join(map(str, out[::-1]))

def DecodeNegBase(nstr, b): #Converts to decimal if nstr == "0": return 0

total = 0 for i, ch in enumerate(nstr[::-1]): total += int(ch) * b**i return total

if __name__=="__main__":

print ("Encode 10 as negabinary (expect 11110)") result = EncodeNegBase(10, -2) print (result) if DecodeNegBase(result, -2) == 10: print ("Converted back to decimal") else: print ("Error converting back to decimal")

print ("Encode 146 as negaternary (expect 21102)") result = EncodeNegBase(146, -3) print (result) if DecodeNegBase(result, -3) == 146: print ("Converted back to decimal") else: print ("Error converting back to decimal")

print ("Encode 15 as negadecimal (expect 195)") result = EncodeNegBase(15, -10) print (result) if DecodeNegBase(result, -10) == 15: print ("Converted back to decimal") else: print ("Error converting back to decimal")</lang>

Output:
Encode 10 as negabinary (expect 11110)
11110
Converted back to decimal
Encode 146 as negaternary (expect 21102)
21102
Converted back to decimal
Encode 15 as negadecimal (expect 195)
195
Converted back to decimal

Racket

<lang racket>#lang racket

(define all-digits (string->list "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz-"))

(define d->i-map (for/hash ((i (in-naturals)) (d all-digits)) (values d i)))

(define max-base (length all-digits))

(define (q/r n d) 

 (let-values (((q r) (quotient/remainder n d)))
   (if (negative? r)
       (values (+ q 1) (- r d))
       (values q r))))

(define (negabase-convertors base) 

 (when (not (integer? base)) (raise "Non-integer base."))
 (when (not (<= 2 (abs base) max-base)) (raise (format "(abs base) must be inside [2 ~a] interval." max-base)))
 (values
  (let ((q/r_base (curryr q/r base)))
    (λ (num)
      (define (checked->base num dig)
        (match num
          [0 (apply string dig)]
          [(app q/r_base num/ rst) (checked->base num/ (cons (list-ref all-digits rst) dig))]))
      (if (integer? num)
          (checked->base num  (if (zero? num) '(#\0) '()))
          (raise "Non-integer number."))))

  (λ (dig)
    (define (loop digs acc)
      (match digs [(list) acc] [(cons a d) (loop d (+ (* acc base) (hash-ref d->i-map a)))]))
    (loop (string->list dig) 0))))

(define-values (->negabinary negabinary->) (negabase-convertors -2))

(define-values (->negaternary negaternary->) (negabase-convertors -3))

(define-values (->negadecimal negadecimal->) (negabase-convertors -10))

(define-values (->nega63ary nega63ary->) (negabase-convertors (- max-base)))

(module+ main 

 (->negaternary 146)
 (->negabinary 10)
 (->negadecimal 15)
 (->nega63ary -26238001742))

(module+ test 

 (require rackunit)

 ;; tests from wikipedia page
 (check-equal? (call-with-values (λ () (q/r 146 -3)) cons) '(-48 . 2))
 (check-equal? (call-with-values (λ () (q/r -48 -3)) cons) '(16 . 0))
 (check-equal? (call-with-values (λ () (q/r 16 -3)) cons) '(-5 . 1))
 (check-equal? (call-with-values (λ () (q/r -5 -3)) cons) '(2 . 1))
 (check-equal? (call-with-values (λ () (q/r 2 -3)) cons) '(0 . 2))

 (define-values (->hexadecimal hexadecimal->) (negabase-convertors 16))
 (check-equal? (->hexadecimal 31) "1F"))</lang>
Output:
"21102"
"11110"
"195"
"Racket"

REXX

Both REXX versions use a type of   assert   (a function call of OK)   that converts the numbers in the
negative base back to the original number in base ten   (and issues an error message if not correct).

version 1 (up to base -10)

<lang rexx>/*REXX pgm converts & displays a base ten integer to a negative base number (up to -10).*/ @=' converted to base '; numeric digits 300 /*be able to handle ginormous numbers. */ n= 10; b= -2; nb=nBase(n,b); say right(n, 20) @ right(b, 3) '────►' nb ok() n=146; b= -3; nb=nBase(n,b); say right(n, 20) @ right(b, 3) '────►' nb ok() n= 15; b=-10; nb=nBase(n,b); say right(n, 20) @ right(b, 3) '────►' nb ok() n=-15; b=-10; nb=nBase(n,b); say right(n, 20) @ right(b, 3) '────►' nb ok() n= 0; b= -5; nb=nBase(n,b); say right(n, 20) @ right(b, 3) '────►' nb ok() exit /*stick a fork in it, we're all done. */ /*──────────────────────────────────────────────────────────────────────────────────────*/ nBase: procedure; parse arg x,r; $= /*obtain args; $ is the integer result.*/ 

      if r<-10 | r>-2 then do; say 'base' r "must be in range: -2 ───► -10"; exit 13; end
                        do  while x\==0         /*keep processing while  X  isn't zero.*/
                        z=x//r;   x=x%r         /*calculate remainder; calculate int ÷.*/
                        if z<0  then do;  z=z-r /*subtract a negative  R  from  Z ◄──┐ */
                                          x=x+1 /*bump  X  by one.                   │ */
                                     end        /*                   Funny "add" ►───┘ */
                        $=z || $                /*prepend new digit (numeral) to result*/
                        end   /*while*/
      return $

/*──────────────────────────────────────────────────────────────────────────────────────*/ ok:  ?=; if pBase(nb, b)\=n then ?=' ◄──error in negative base calculation'; return ? /*──────────────────────────────────────────────────────────────────────────────────────*/ pBase: procedure; parse arg x,r; p=0; $=0 /*obtain args; $ is the integer result.*/ 

      if r<-10 | r>-2 then do; say 'base' r "must be in range: -2 ───► -10"; exit 13; end
      L=length(x);    do j=L  by -1  for L      /*process each of the numerals in  X.  */
                      $=$ + substr(x,j,1)*r**p  /*add value of a numeral to $ (result).*/
                      p=p+1                     /*bump the power by 1.                 */
                      end   /*j*/               /* [↓]  process the number "bottom-up".*/
      return $</lang>
output   when using the default inputs:
                  10  converted to base   -2 ────► 11110
                 146  converted to base   -3 ────► 21102
                  15  converted to base  -10 ────► 195
                 -15  converted to base  -10 ────► 25
                   0  converted to base   -5 ────► 0

version 2 (up to base -71)

This REXX version supports up to negative base   ─71,   but it may not be compatible to other programming examples
because the symbols (glyphs or numerals) used herein may not be in the same exact order.   The symbols represented
in this REXX program should be able to represent   any   programming language used on Rosetta Code. <lang rexx>/*REXX pgm converts & displays a base ten integer to a negative base number (up to -71).*/ @=' converted to base '; numeric digits 300 /*be able to handle ginormous numbers. */ n= 10; b= -2; nb=nBase(n,b); say right(n,20) @ right(b,3) '────►' nb ok() n= 146; b= -3; nb=nBase(n,b); say right(n,20) @ right(b,3) '────►' nb ok() n= 15; b=-10; nb=nBase(n,b); say right(n,20) @ right(b,3) '────►' nb ok() n= -15; b=-10; nb=nBase(n,b); say right(n,20) @ right(b,3) '────►' nb ok() n= 0; b= -5; nb=nBase(n,b); say right(n,20) @ right(b,3) '────►' nb ok() n=-6284695; b=-62; nb=nBase(n,b); say right(n,20) @ right(b,3) '────►' nb ok() exit /*stick a fork in it, we're all done. */ /*──────────────────────────────────────────────────────────────────────────────────────*/ _Base: !='0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz /*+-!éáµ' /*sym*/ 

      parse arg $;        m=length(!);            L=length(x);              p=0
      if r<-m | r>-2 then do;  say 'base' r "must be in range: -2 ───► -"m; exit 13;  end
      return

/*──────────────────────────────────────────────────────────────────────────────────────*/ nBase: procedure; parse arg x,r; call _Base /*get args; $ will be integer result. */ 

                   do  while x\==0              /*keep processing while  X  isn't zero.*/
                   z=x//r;           x= x%r     /*calculate remainder; calculate int ÷.*/
                   if z<0  then do;  z= z-r     /*subtract a negative  R  from  Z ◄──┐ */
                                     x= x+1     /*bump  X  by one.                   │ */
                                end             /*                   Funny "add" ►───┘ */
                   $=substr(!, z+1, 1)$         /*prepend the new numeral to the result*/
                   end   /*while*/
      return $

/*──────────────────────────────────────────────────────────────────────────────────────*/ ok: if pBase(nb,b)\=n then return ' ◄──error in negative base calculation'; return /*──────────────────────────────────────────────────────────────────────────────────────*/ pBase: procedure; parse arg x,r; call _Base 0 /*get args; $ will be integer result. */ 

                   do j=L  by -1  for L         /*process each of the numerals in  X.  */
                   v=pos( substr(x,j,1), !) - 1 /*use base  R  for the numeral's value.*/
                   $=$ + v * r**p;       p= p+1 /*add it to $ (result); bump power by 1*/
                   end   /*j*/                  /* [↑]  process the number "bottom-up".*/
      return $</lang>
output   when using the default inputs:
                  10  converted to base   -2 ────► 11110
                 146  converted to base   -3 ────► 21102
                  15  converted to base  -10 ────► 195
                 -15  converted to base  -10 ────► 25
                   0  converted to base   -5 ────► 0
            -6284695  converted to base  -62 ────► Rexx

Ring

<lang ring>

  1. Project : Negative base numbers

negs = [[146,-3],[21102,-3],[10,-2],[11110,-2],[15,-10],[195,-10]] for n = 1 to len(negs) step 2 

    enc = encodeNegBase(negs[n][1],negs[n][2])
    encstr = showarray(enc)
    dec = decodeNegBase(negs[n+1][1],negs[n+1][2])
    see "" + negs[n][1] + " encoded in base " + negs[n][2] + " = " + encstr + nl
    see "" + negs[n+1][1] + " decoded in base " + negs[n+1][2] + " = " + dec + nl

next

func encodeNegBase(n,b) 

      out = []
      while n != 0
              rem = (n%b)
              if rem < 0
                 rem = rem - b 
              ok 
              n = ceil(n/b)
              rem = fabs(rem)
              add(out,rem)
      end
      out = reverse(out)
      return out

func decodeNegBase(n,b) 

       out = 0
       n = string(n)
       for nr = len(n) to 1 step -1
            out = out + n[nr]*pow(b,len(n)-nr)
       next
       return out

func showarray(vect) 

       svect = ""
       for n = 1 to len(vect)
             svect = svect + vect[n]
       next
       return svect

</lang> Output: 

146 encoded in base -3 = 21102
21102 decoded in base -3 = 146
10 encoded in base -2 = 11110
11110 decoded in base -2 = 10
15 encoded in base -10 = 195
195 decoded in base -10 = 15

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>

Output:
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


Sidef

Translation of: Perl 6
Translation of: Python

<lang ruby>func EncodeNegBase(Num n, Num b { .~~ (-36 .. -2) }) { 

   var out = []
   var r = 0
   while (n) {
       (n, r) = divmod(n, b)
       if (r < 0) {
           n += 1
           r -= b
       }
       out << r.base(-b)
   }
   return (out.join.flip || "0")

}

func DecodeNegBase(Str s, Num b { .~~ (-36 .. -2) }) { 

   var total = 0
   for i,c in (s.flip.chars.kv) {
       total += (Num(c, -b) * b**i)
   }
   return total

}

say (" 10 in base -2: ", EncodeNegBase(10, -2)) say ("146 in base -3: ", EncodeNegBase(146, -3)) say (" 15 in base -10: ", EncodeNegBase(15, -10))

say '-'*25

say ("11110 from base -2: ", DecodeNegBase("11110", -2)) say ("21102 from base -3: ", DecodeNegBase("21102", -3)) say (" 195 from base -10: ", DecodeNegBase("195", -10))

say '-'*25

  1. Extra

say ("25334424 in base -31: ", EncodeNegBase(25334424, -31)) say ("sidef from base -31: ", DecodeNegBase("sidef", -31))</lang>

Output:
 10 in base  -2: 11110
146 in base  -3: 21102
 15 in base -10: 195
-------------------------
11110 from base  -2: 10
21102 from base  -3: 146
  195 from base -10: 15
-------------------------
25334424 in base -31: sidef
sidef  from base -31: 25334424

zkl

<lang zkl>fcn toNBase(n,radix){ 

  var [const] cs=[0..9].chain(["a".."z"]).pump(String);  //"0123456789abcd..z"
  _assert_(-37 < radix < -1,"invalid radix");
  digits:=List();
  while(n){ reg r;
     n,r=n.divr(radix);	// C compiler semantics
     if(r<0){ n+=1; r-=radix; }
     digits.append(r);
  }
  digits.reverse().pump(String,cs.get);

}

fcn toInt(str,radix){ // the toInt(radix) method radix is 2..36 

  str.reduce('wrap(s,d,rdx){ s*radix + d.toInt(rdx); },0,radix.abs());

}</lang> <lang zkl>ns:=T( T(10,-2), T(146,-3), T(15,-10), T(107,-16), T(41371458,-36), T(44661,-36) ); results:=ns.pump(List,Void.Xplode,toNBase); foreach nb,r in (ns.zip(results)){ 

  _,b:=nb;
  println("%10d.base(%3d) = \"%s\" --> %d".fmt(nb.xplode(),r,toInt(r,b)));

}</lang>

Output:
        10.base( -2) = "11110" --> 10
       146.base( -3) = "21102" --> 146
        15.base(-10) = "195" --> 15
       107.base(-16) = "1ab" --> 107
  41371458.base(-36) = "perl6" --> 41371458
     44661.base(-36) = "zkl" --> 44661

References

  1. ↑ Negabinary on Wolfram Mathworld
  2. ↑ Negative base on Wikipedia
Retrieved from "https://rosettacode.org/wiki/Negative_base_numbers?oldid=272044"