You can use CoCreateGuid API to general GUID. Please follow these codes.
GUID gdn; CoCreateGuid(&gdn); Guid gd(gdn); String^ guid=gd.ToString();
Best regards, Jesse
Jesse Jiang [MSFT] MSDN Community Support | Feedback to us
Platform::Guid A 128-bit nonnumeric value (a GUID) in the Platform namespace.
See Guid::Guid Constructor