IPrint

Module1.bas

Option Explicit

Private Type GUID
    Data1 As Long
    Data2 As Integer
    Data3 As Integer
    Data4(0 To 7) As Byte
End Type

'https://msdn.microsoft.com/en-us/library/52e6es3z.aspx
Private Declare PtrSafe _
Function AtlComQIPtrAssign Lib "atl110.dll" ( _
    ByRef pp As IUnknown, _
    ByVal lp As IUnknown, _
    ByRef riid As GUID _
) As IUnknown

Private Declare PtrSafe _
Function IIDFromString Lib "ole32.dll" ( _
    ByVal lpsz As LongPtr, _
    ByRef lpiid As GUID _
) As Long

Const IID_IPrint = "{b722bcc9-4e68-101b-a2bc-00aa00404770}"
'https://msdn.microsoft.com/en-us/library/windows/desktop/ms693796%28v=vs.85%29.aspx

Private Declare PtrSafe Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" (Destination As Any, Source As Any, ByVal Length As LongPtr)


Sub hoge()

    Dim hr As Long
    Dim iid As GUID
    hr = IIDFromString(StrPtr(IID_IPrint), iid)

    Dim unk As IUnknown
    Dim o As Workbook
    Set o = Excel.Application.Workbooks(1)
    
    AtlComQIPtrAssign unk, o, iid
    Debug.Print unk Is Nothing

    CopyMemory unk, Nothing, 4

End Sub