What's the C++ version of Guid.NewGuid()?
I think CoCreateGuid is what you're after. Example:
GUID gidReference;
HRESULT hCreateGuid = CoCreateGuid( &gidReference );
UuidCreate() in Win32 API has exactly the same effect. However you need to pass an address of the variable that will receive the generated value:
UUID newId;
UuidCreate( &newId );
I believe Guid.NewGuid() simply maps onto it inside the .NET runtime.