I am using Base 64 to create shorter URLs as described, and I'm not too familiar with all the maths of bytes and bases.

Public Shared Function encUC(ByVal uniqueCode As String) As String

Dim val As Int64 = Convert.ToInt64(uniqueCode)
Dim retVal As String

Dim tinyByte() = System.BitConverter.GetBytes(val)

'NB THIS WILL WORK FOR A MAX OF 12 DIGIT CODES
'ReDim Preserve tinyByte(4)

Dim tinyCode = Base64.Base64Encoder.ToBase64(tinyByte)

retVal = Replace(tinyCode, "=", "_")
retVal = Replace(retVal, "/", "-")
retVal = Replace(retVal, "+", "|")

Return retVal

End Function

When I encode it seems to not give me the least possible characters in the base64 string

eg

1000001728 encodes as wNCaOwAAAAA_

So i have shortened the byte array :
ReDim Preserve tinyByte(4)

Which is fine as my codes are a max of 12 digits, but not very elegant.

Can you suggest anything?

ALSO

When I decode a 32 bit integer (8 digit code)

Public Shared Function decUC(ByVal encCode As String) As String

Dim repCode As String = encCode
repCode = Replace(repCode, "_", "=")
repCode = Replace(repCode, "-", "/")
repCode = Replace(repCode, "|", "+")

Dim origByte(7) As Byte
origByte = Base64.Base64Encoder.FromBase64(repCode)
ReDim Preserve origByte(7)

Return System.BitConverter.ToInt64(origByte, 0)

End Function

if I don't use ReDim Preserve origByte(7) it gives me an exception on the

Return System.BitConverter.ToInt64(origByte, 0) (array to short)

As I won't always know if i'm getting an 8 or 12 digital code – I want my functions to cater for both. Any ideas?

My thanks again for a really great post that ended hours of midnight hunting