$INCLUDE "windowssdk.inc"

TYPE DateType
	UINT LowDW
	UINT HighDW
ENDTYPE

UNION uDT
	UINT64 qVar
	DateType dtVar
ENDUNION
  uDT u

SYSTEMTIME st
FILETIME ft

INT rtn
UINT64 qDAY = 24*60*60*10000000 '1 day in nano seconds

'First get the system time so that all the other structure members are filled
	GetSystemTime(st)
'Set up the SYSTEMTIME structure with the original date like so:
'	st.wDay = 30
'	st.wMonth = 11
'	st.wYear = 2023
	PRINT
	PRINT USING("Original Date = ##/##/####",st.wDay,st.wMonth,st.wYear)

' Convert the system time to file time
	rtn = SystemTimeToFileTime(st,ft)

' Move the FILETIME info into a UINT64 variable
' and add days using the Quad variable (this is how M$ recommends doing it)
	u.dtVar.LowDW = ft.dwLowDateTime
	u.dtVar.HighDW = ft.dwHighDateTime

'Add days using the Quad variable.
	u.qVar += (qDAY * 1) 'Add 1 day
	ft.dwLowDateTime = u.dtVar.LowDW
	ft.dwHighDateTime = u.dtVar.HighDW

' Convert the file time to system time
	rtn = FileTimeToSystemTime(ft,st)

' Now your new date will be in the SYSTEMTIME structure members
	PRINT
	PRINT "Date plus one day"
	PRINT USING("##/##/####",st.wDay,st.wMonth,st.wYear)

	PRINT
DO:UNTIL INKEY$<>""
	CLOSECONSOLE
END