Why is the GUID structure declared the way it is?
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07-07-2019 - |
Question
In rpc.h, the GUID structure is declared as follows:
typedef struct _GUID
{
DWORD Data1;
WORD Data2;
WORD Data3;
BYTE Data[8];
} GUID;
I understand Data1, Data2, and Data3. They define the first, second, and third sets of hex digits when writing out a GUID (XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXX).
What I never understood was why the last 2 groups were declared together in the same byte array. Wouldn't this have made more sense (and been easier to code against)?
typedef struct _GUID
{
DWORD Data1;
WORD Data2;
WORD Data3;
WORD Data4;
BYTE Data5[6];
} GUID;
Anyone know why it is declared this way?
OTHER TIPS
http://en.wikipedia.org/wiki/Globally_Unique_Identifier and http://www.opengroup.org/onlinepubs/9629399/apdxa.htm (DCE's orginal representation, you can see the grouping of bits there in a table)
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