Data commit

Task/Negative-base-numbers/VBA/negative-base-numbers.vba

@@ -0,0 +1,66 @@
+Const DIGITS = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
+Dim Str(63) As String
+Private Function mod2(a As Long, b As Integer) As Long
+    mod2 = a - (a \ b) * b
+End Function
+Private Function swap(a As String, b As String)
+    Dim t As String
+    t = a
+    a = b
+    b = t
+End Function
+Private Function EncodeNegativeBase(ByVal n As Long, base As Integer) As String
+    Dim ptr, idx As Long
+    Dim rem_ As Long
+    Dim result As String
+    If base > -1 Or base < -62 Then
+        EncodeNegativeBase = result
+    Else
+        If n = 0 Then
+            EncodeNegativeBase = "0"
+        Else
+            ptr = 0
+            Do While n <> 0
+                rem_ = mod2(n, base)
+                n = n \ base
+                If rem_ < 0 Then
+                    n = n + 1
+                    rem_ = rem_ - base
+                End If
+                result = result & Mid(DIGITS, rem_ + 1, 1)
+            Loop
+        End If
+    End If
+    EncodeNegativeBase = StrReverse(result)
+End Function
+Private Function DecodeNegativeBase(ns As String, base As Integer) As Long
+    Dim total As Long, bb As Long
+    Dim i As Integer, j As Integer
+    If base < -62 Or base > -1 Then DecodeNegativeBase = 0
+    If Mid(ns, 1, 1) = 0 Or (Mid(ns, 1, 1) = "0" And Mid(ns, 2, 1) = 0) Then DecodeNegativeBase = 0
+    i = Len(ns)
+    total = 0
+    bb = 1
+    Do While i >= 1
+        j = InStr(1, DIGITS, Mid(ns, i, 1), vbTextCompare) - 1
+        total = total + j * bb
+        bb = bb * base
+        i = i - 1
+    Loop
+    DecodeNegativeBase = total
+End Function
+Private Sub Driver(n As Long, b As Integer)
+    Dim ns As String
+    Dim p As Long
+    ns = EncodeNegativeBase(n, b)
+    Debug.Print CStr(n); " encoded in base "; b; " = "; ns
+    p = DecodeNegativeBase(ns, b)
+    Debug.Print ns; " decoded in base "; b; " = "; p
+    Debug.Print
+End Sub
+Public Sub main()
+    Driver 10, -2
+    Driver 146, -3
+    Driver 15, -10
+    Driver 118492, -62
+End Sub