' Various Date Routines by Bill Haesslein on 2008-08-24
' Date and Easter calculations from Marcos J. Montes
' Stripped down from original Date_Routines.iwb and modified by Brian Pugh on 2024-02-28

autodefine "off"

$INCLUDE "windowssdk.inc"

TYPE DateType
	UINT LowDW
	UINT HighDW
ENDTYPE

UNION uDT
	UINT64 qVar
	DateType dtVar
ENDUNION

SYSTEMTIME st
	FILETIME ft
	uDT s,e,d

INT iVar,rtn
ISTRING sDate[12],eDate[12],swapDate[12]

openconsole

'Must be entered in Year, Month and Day order
'sDate = Start Date  -  eDate = End Date

sDate="2000-01-01" 'Your birthday or any date you put in
	eDate=Date$("yyyy-MM-dd") 'Today's date
	ElapsedDays(sDate,eDate)

PRINT
	print "Elapsed Days since "+sDate+":"+STR$(iVar)
	PRINT
	PRINT "Press any key to close..."

DO:UNTIL INKEY$<>""
	closeconsole
end

'The clever stuff...
SUB ElapsedDays(sDate:string,eDate:string)
' Make sure that eDate > sDate
IF eDate>sDate
	swapDate=""
else
	swapDate=sDate
	sDate=eDate
	eDate=swapDate
endif
'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.wYear=val(mid$(sDate,1,4))
	st.wMonth=val(mid$(sDate,6,2))
	st.wDay=val(mid$(sDate,9,2))
'Convert the system time to filetime
	rtn=SystemTimeToFileTime(st,ft)
'Move the FILETIME info into a UINT64 variable
'and add days using the Quad variable (this is how MS recommends doing it)
	s.dtVar.LowDW=ft.dwLowDateTime
	s.dtVar.HighDW=ft.dwHighDateTime
'First get the system time so that all the other structure members are filled
	GetSystemTime(st)
'Set up the SYSTEMTIME structure with the original date like so:
	st.wYear=val(mid$(eDate,1,4))
	st.wMonth=val(mid$(eDate,6,2))
	st.wDay=val(mid$(eDate,9,2))
'Convert the system time to filetime
	rtn=SystemTimeToFileTime(st,ft)
'Move the FILETIME info into a UINT64 variable
'and add days using the Quad variable (this is how MS recommends doing it)
	e.dtVar.LowDW=ft.dwLowDateTime
	e.dtVar.HighDW=ft.dwHighDateTime
	d.qVar=e.qVar-s.qVar
	iVar=d.qVar/(24*60*60*10000000)
return iVar 'iVar contains number of Elapsed Days
endsub