Guid Byte Order in .NET

by

It appears that MS are storing the five parts in a structure.
The first 4 parts are either 2 or 4 bytes long and are therefore probably stored as a native type (ie. WORD and DWORD) in little endian format. The last part is 6 bytes long and it therefore handled differently (probably an array).

Does the Spec state that the GUID is stored in big-endian order, or that the storage of parts are in that order but the indiviual parts may be implementation specific?

EDIT:

From the UUID spec, section 4.1.2. Layout and Byte Order (emphasis mine):

To minimize confusion about bit assignments within octets, the UUID
record definition is defined only in terms of fields that are
integral numbers of octets. The fields are presented with the most
significant one first.

…

In the absence of explicit application or presentation protocol
specification to the contrary, a UUID is encoded as a 128-bit object,
as follows:

The fields are encoded as 16 octets, with the sizes and order of
the fields defined above, and with each field encoded with the Most
Significant Byte first (known as network byte order).

It might be that MS have stored the bytes in the correct order, but have not bothered to network-to-host order the WORD and DWORD parts for presentation (which appears to be ok according to the spec, at least by my unskilled reading of it.)

More Related Contents:

  1. How Random is System.Guid.NewGuid()?
  2. How Random is System.Guid.NewGuid()? (Take two)
  3. Sequential GUID in Linq-to-Sql?
  4. How securely unguessable are GUIDs?
  5. What is the string length of a GUID?
  6. How are .NET 4 GUIDs generated?
  7. How do I take a good crash dump for .NET?
  8. Choosing between MEF and MAF (System.AddIn)
  9. Play audio from a stream using C#
  10. Using the field of an object as a generic Dictionary key
  11. Double-checked locking in .NET
  12. How to Create Deterministic Guids
  13. Maximum array length quota
  14. RegEx: Smallest possible match or nongreedy match
  15. Best way to use StructureMap to implement Strategy pattern
  16. BitmapImage in WPF does lock file
  17. The library hostpolicy.dll was not found
  18. CLIPBRD_E_CANT_OPEN error when setting the Clipboard from .NET
  19. Can’t find ADO.net Entity Data Model template in VS2017
  20. ActiveX, installation doesn’t work
  21. How to get the application executable name in WindowsC++/CLI?
  22. Read MAC Address from network adapter in .NET
  23. How to create System.IO.StreamWriter with Encoding in Powershell?
  24. .NET NUnit test – Assembly.GetEntryAssembly() is null
  25. DispatcherTimer vs a regular Timer in WPF app for a task scheduler
  26. Calculate System.Decimal Precision and Scale
  27. Does .NET assembly size affect performance?
  28. How do I specify XML serialization attributes to support namespace prefixes during deserialization in .NET?
  29. Where can I find a TPL dataflow version for 4.0?
  30. How to perform merge sort using LINQ?

Leave a Comment