Converting GUIDs to Strings

Developer: RhinoScript
Summary: Demonstrates how convert an array of bytes containing a GUID to a string.

I've written a RhinoScript function which calls a method on a COM object that returns an array of bytes containing a GUID. Is there any way that I can turn this into a string?

Yes, this is possible, but it takes a little work. The logical format of a GUID in memory is not in the same order as the bytes are in the string. A GUID stored in binary format in memory is a sixteen byte structure in the following format:

 DWORD-WORD-WORD-BYTE BYTE-BYTE BYTE BYTE BYTE BYTE BYTE

Where a WORD consists of two bytes and a DWORD consistes of four bytes. They are stored in memory in order from the least to the most significant, or “little endian”, on Intel-based systems. So, you need to make sure you decode the array in the correct order

The following example RhinoScript code demonstrates how to convert an array of bytes containing a GUID to a string.

 ' Returns single digit bytes, like 0, as "00", not "0"
 Function HexByte(b)
   HexByte = Right("0" & Hex(b), 2)
 End Function 
 
 ' Converts a GUID to a string
 Function GuidToString(ByteArray)
   Dim Binary, S
   Binary = CStr(ByteArray)
   ' Uncomment if you want opening paren
   ' S = "{"
   S = S & HexByte(AscB(MidB(Binary, 4, 1)))
   S = S & HexByte(AscB(MidB(Binary, 3, 1)))
   S = S & HexByte(AscB(MidB(Binary, 2, 1)))
   S = S & HexByte(AscB(MidB(Binary, 1, 1)))
   S = S & "-"  
   S = S & HexByte(AscB(MidB(Binary, 6, 1)))
   S = S & HexByte(AscB(MidB(Binary, 5, 1)))
   S = S & "-"  
   S = S & HexByte(AscB(MidB(Binary, 8, 1)))
   S = S & HexByte(AscB(MidB(Binary, 7, 1)))
   S = S & "-"  
   S = S & HexByte(AscB(MidB(Binary, 9, 1)))
   S = S & HexByte(AscB(MidB(Binary, 10, 1)))
   S = S & "-"  
   S = S & HexByte(AscB(MidB(Binary, 11, 1)))
   S = S & HexByte(AscB(MidB(Binary, 12, 1)))
   S = S & HexByte(AscB(MidB(Binary, 13, 1)))
   S = S & HexByte(AscB(MidB(Binary, 14, 1)))
   S = S & HexByte(AscB(MidB(Binary, 15, 1)))
   S = S & HexByte(AscB(MidB(Binary, 16, 1)))
   ' Uncomment if you want closing paren
   ' S = S & "}"
   GuidToString = S
 End Function