Accessing Guid members in C#

Question

Hello,

In C++ we can access members of a guid in the following way:

GUID guid = {0};
CoCreateGuid(&guid);
dwRand = guid.Data1 & 0x7FFFFFFF;

The structure of guid in C++ is:

Data 1 - unsigned long
Data 2 - unsigned short
Data 3 - unsigned short
Data 4 - unsigned char

Question: How to translate the third line in the C++ code (dwRand = guid.Data1 & 0x7FFFFFFF;). In other words - how to access guid members? There's no such thing in C#.

Thanks in advance!

Answer 1

You can use Guid.ToByteArray to get the values as bytes, but there are no accessor methods/properties for the "grouped" bytes. You could always write them as extension methods if you're using C# 3 though.

Answer 2

You can create a structure:

public struct MyGuid
{
    public int Data1;
    public short Data2;
    public short Data3;
    public byte[] Data4;

    public MyGuid(Guid g)
    {
        byte[] gBytes = g.ToByteArray();
        Data1 = BitConverter.ToInt32(gBytes, 0);
        Data2 = BitConverter.ToInt16(gBytes, 4);
        Data3 = BitConverter.ToInt16(gBytes, 6);
        Data4 = new Byte[8];
        Buffer.BlockCopy(gBytes, 8, Data4, 0, 8);
    }

    public Guid ToGuid()
    {
        return new Guid(Data1, Data2, Data3, Data4);
    }
}

Now, if you want to modify a Guid:

Guid g = GetGuidFromSomewhere();
MyGuid mg = new MyGuid(g);
mg.Data1 &= 0x7FFFFFFF;
g = mg.ToGuid();