.NET Native GUID conversion

Question

I have an external database that is feeding information to me. One saves their data as native GUID format and my other data source supplies standard .NET GUID format string.

Answer 1

If I understand the question correctly, I posted extension methods that do this in How to read a .NET Guid into a Java UUID.

Answer 2

If in fact you are dealing with Endian issues, you'll have no choice but to parse the string yourself into the constituent parts of the Guid switch the Endianness, and then create a Guid that you would then use.

Answer 3

To see if the input is in little Endian or not BitConverter.IsLittleEndinan() helps.

I just had to do this same thing and using Paul Smith's answer above I got it working with this code. Derived off his code but with a fix on last byte swap order and condensed to one flip ensuring guid.FlipEndian().FlipEndian() == guid.

C# Code:

public static class Extensions
{
    /// <summary>
    /// A CLSCompliant method to convert a big-endian Guid to little-endian
    /// and vice versa.
    /// The Guid Constructor (UInt32, UInt16, UInt16, Byte, Byte, Byte, Byte,
    ///  Byte, Byte, Byte, Byte) is not CLSCompliant.
    /// </summary>
    [CLSCompliant(true)]
    public static Guid FlipEndian(this Guid guid)
    {
        var newBytes = new byte[16];
        var oldBytes = guid.ToByteArray();

        for (var i = 8; i < 16; i++)
            newBytes[i] = oldBytes[i];

        newBytes[3] = oldBytes[0];
        newBytes[2] = oldBytes[1];
        newBytes[1] = oldBytes[2];
        newBytes[0] = oldBytes[3];
        newBytes[5] = oldBytes[4];
        newBytes[4] = oldBytes[5];
        newBytes[6] = oldBytes[7];
        newBytes[7] = oldBytes[6];

        return new Guid(newBytes);
    }
}

VB.net code (Translated from online service):

Imports System.Runtime.CompilerServices

Module ModuleExtension

    ''' <summary>
    ''' A CLSCompliant method to convert a big-endian Guid to little-endian
    ''' and vice versa.
    ''' The Guid Constructor (UInt32, UInt16, UInt16, Byte, Byte, Byte, Byte,
    '''  Byte, Byte, Byte, Byte) is not CLSCompliant.
    ''' </summary>
    <Extension()>
    Public Function FlipEndian(guid As Guid) As Guid
        Dim newBytes = New Byte(15) {}
        Dim oldBytes = guid.ToByteArray()

        For i As Integer = 8 To 15
            newBytes(i) = oldBytes(i)
        Next

        newBytes(3) = oldBytes(0)
        newBytes(2) = oldBytes(1)
        newBytes(1) = oldBytes(2)
        newBytes(0) = oldBytes(3)
        newBytes(5) = oldBytes(4)
        newBytes(4) = oldBytes(5)
        newBytes(6) = oldBytes(7)
        newBytes(7) = oldBytes(6)

        Return New Guid(newBytes)
    End Function

End Module