Task: Straddling checkerboard
C++: #include <iostream>
#include <string>
#include <map>
#include <algorithm> 
using namespace std;

class StraddlingCheckerboard
{
  map<char, string> table;
  char first[10], second[10], third[10];
  int rowU, rowV;

public:
  StraddlingCheckerboard(const string &alphabet, int u, int v)
  {
    rowU = min(u, v);
    rowV = max(u, v);

    for(int i = 0, j = 0; i < 10; ++i)
    {
      if(i != u && i != v)
      {
        first[i] = alphabet[j];
        table[alphabet[j]] = '0' + i;
        ++j;
      }

      second[i] = alphabet[i+8];
      table[alphabet[i+8]] = '0' + rowU;
      table[alphabet[i+8]] += '0' + i;

      third[i] = alphabet[i+18];
      table[alphabet[i+18]] = '0' + rowV;
      table[alphabet[i+18]] += '0' + i;
    }
  }

  string encode(const string &plain)
  {
    string out;
    for(int i = 0; i < plain.size(); ++i)
    {
      char c = plain[i];
      if(c >= 'a' && c <= 'z')
        c += 'A' - 'a';

      if(c >= 'A' && c <= 'Z')
        out += table[c];
      else if(c >= '0' && c <= '9')
      {
        out += table['/'];
        out += c;
      }
    }
    return out;
  }

  string decode(const string &cipher)
  {
    string out;
    int state = 0;
    for(int i = 0; i < cipher.size(); ++i)
    {
      int n = cipher[i] - '0';
      char next = 0;

      if(state == 1)
        next = second[n];
      else if(state == 2)
        next = third[n];
      else if(state == 3)
        next = cipher[i];
      else if(n == rowU)
        state = 1;
      else if(n == rowV)
        state = 2;
      else
        next = first[n];

      if(next == '/')
        state = 3;
      else if(next != 0)
      {
        state = 0;
        out += next;
      }
    }
    return out;
  }
};

VB: 

Function encrypt(ByVal originalText, ByVal alphabet, blank1, blank2)
  Const notEscape = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ."
  Dim i, j, curChar, escChar, outText
  Dim cipher  
  Set cipher = CreateObject("Scripting.Dictionary")
  
  alphabet = UCase(alphabet) : j = 0
  For i = 1 To 28
    curChar = Mid(alphabet, i, 1)
    Select Case True
      Case i>= 1 And i<= 8
        If j = blank1 Or j = blank2 Then j = j + 1  
		cipher.Add curChar, CStr(j)
        j = j + 1
      Case i>= 9 And i<=18
		cipher.Add curChar, CStr(blank1) & CStr(i -  9)
      Case i>=19 And i<=28
		cipher.Add curChar, CStr(blank2) & CStr(i - 19)
    End Select 
    If InStr(notEscape, curChar) = 0 Then
      escChar = curChar
      
    End If
  Next 
  For i = 0 To 9: cipher.Add CStr(i), cipher(escChar) & CStr(i): Next 
  
  originalText = UCase(originalText)
  For i = 1 To Len(originalText)
    outText = outText & cipher(Mid(originalText, i, 1))
  Next 
  encrypt=outText
End Function 
 
Function decrypt(ByVal cipherText, ByVal alphabet, blank1, blank2)
  Const notEscape = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ."
  Dim i, j, curChar, escCipher, outText
  Dim cipher  
  Set cipher = CreateObject("Scripting.Dictionary")
  
  alphabet = UCase(alphabet) : j = 0
  For i = 1 To 28
    curChar = Mid(alphabet, i, 1)
    Select Case True
      Case i>= 1 And i<= 8
        If j = blank1 Or j = blank2 Then j = j + 1  
		cipher.Add CStr(j),curChar
        j = j + 1
      Case i>= 9 And i<=18
        cipher.Add CStr(blank1) & CStr(i -  9), curChar
      Case i>=19 And i<=28
        cipher.Add CStr(blank2) & CStr(i - 19), curChar
    End Select 
    If InStr(notEscape, curChar) = 0 Then
      
      arrayKeys=cipher.keys
      escCipher = arrayKeys(cipher.count-1)
      
    End If
  Next 
  For i = 0 To 9: cipher.Add escCipher & CStr(i), CStr(i): Next 
  
  i = 1
  Do While i <= Len(cipherText)
    curChar = Mid(cipherText, i, 1)
    If curChar = CStr(blank1) Or curChar = CStr(blank2) Then
      curChar = Mid(cipherText, i, 2)
      If curChar = escCipher Then curChar = Mid(cipherText, i, 3)
    End If 
    outText = outText & cipher(curChar)
    i = i + Len(curChar)
  Loop 
  decrypt=outText
End Function 
 
  message = "One night-it was on the twentieth of March, 1888-I was returning"
  cipher = "HOLMESRTABCDFGIJKNPQUVWXYZ./"
  
  
  
  
  Buffer=Buffer & "Original: " & message & vbCrlf 
  encoded = encrypt(message, cipher, 3, 7)
  Buffer=Buffer &  "encoded: " & encoded & vbCrlf
  decoded = decrypt(encoded, cipher, 3, 7)
  Buffer=Buffer &  "decoded: " & decoded & vbCrlf
  Wscript.Echo Buffer