Adding 365 days to a year field

[Brian]

Hello,

Brian's back! I have this field containing a date, looking like this: 20140711

I need to add one year on (ie, 365 days) and write the new date into another field. Anybody got a routine
or have an idea how to do this?

BTW, it's not an SQL database, just a csv text file

Thanks a lot,

Brian

[LarryMc]

Are you wanting to add a year
1. ignoring leap years or
2. account for leap years or
3. strictly add 365 days?

[Sam]

STRING OldDate = "20140711"
STRING NewDate

NewDate = STR$(VAL(LEFT$(OldDate, 4)) + 1) + MID$(OldDate, 5, LEN(OldDate))

[Brian]

Hi, Larry,

Well, it would have to include leap years for it to be correct. There is a sample posted here somewhere,
but I tried it last night, and the returned day was out by one day, and eventually it crashes

Sam: Good try, but you have to turn your source date into a Julian number, add the days required,
and turn that number back into a readable date. I wish it was that easy!

Brian

[LarryMc]

These routines were written fo CBasic but are easy enough to adapt.

Code Select Expand

sub getJulian(useYear:int,useMonth:int,useDay:int)
'   Returns the Julian Date from year,month,day input
   ly = isLeapYear(useYear)
   'not counting current year
   YearsPassed = useYear - 1901
   DaysInFullYears = YearsPassed * 365
'   The function is only valid from 1/1/1901 to 31/12/2099 so shortcut leap year calc is OK
   LeapYearsPassed = int(YearsPassed/4)
   julian = DaysInFullYears + LeapYearsPassed - 1
   yearToDate=0
   select useMonth
       case 1
           yearToDate = 0
       case 2
           yearToDate = 31
       case 3
           yearToDate = 59 + ly
       case 4
           yearToDate = 90 + ly
       case 5
           yearToDate = 120 + ly
           case 6
           yearToDate = 151 + ly
       case 7
           yearToDate = 181 + ly
       case 8
           yearToDate = 212 + ly
       case 9
           yearToDate = 243 + ly
       case 10
           yearToDate = 273 + ly
       case 11
           yearToDate = 304 + ly
       case 12
           yearToDate = 334 + ly
   endselect
   retval = julian +  yearToDate + useDay
return retval

sub getDate$(jDate;int, localsetting:int),string
'   Return the date from jDate
'   localsetting 1 is mm/dd/yyyy format
'   local setting 2 is dd/mm/yyyy
   TheYear = 0:TheMonth = 0:TheDay = 0
   aYears = int(jDate/365.25)+1
   year = 1901:jDate = jDate + 1:ly = 0
   FOR i = 1 to aYears
       IF jDate <= (365 + ly)
           TheYear=year
           goto endfor
       ENDIF
       jDate =jDate - (365+ly)
       year = year + 1
       ly = isLeapYear(year)
           LABEL endfor
   NEXT i
   IF jDate <= 0
'       "Sorry but that date is out of my range"
       retval$ = "bad date"
       goto endjDate
   ENDIF
   'select jDate
   IF jDate <= 31
     'january
           TheMonth = 1
           TheDay = jDate
     ENDIF
   IF jDate > 31  & jDate <= 59 + ly
     'february
           TheMonth = 2
           TheDay = jDate - 31 + ly
     ENDIF
   IF jDate > 59 + ly & jDate <= 90 + ly
     'march   
           TheMonth = 3
           TheDay = jDate - 59 + ly
     ENDIF
   IF jDate > 90 + ly & jDate <= 120 + ly
     'april
           TheMonth = 4
           TheDay = jDate - 90 + ly
     ENDIF
   IF jDate > (120 + ly) & jDate <= (151 + ly)
     ' may
           TheMonth = 5
           TheDay = jDate - 120 + ly
     ENDIF
   IF jDate > 151 + ly & jDate <= 181 + ly
     ' june
           TheMonth = 6
           TheDay = jDate - 151 + ly
     ENDIF
   IF jDate > 181 + ly & jDate <= 212 + ly
     ' july
           TheMonth = 7
           TheDay = jDate - 181 + ly
     ENDIF
   IF jDate > 212 + ly & jDate <= 243 + ly
     ' august
           TheMonth = 8
           TheDay = jDate - 212 + ly
     ENDIF
   IF jDate > 243 + ly & jDate <= 273 + ly
     ' september
           TheMonth = 9
           TheDay = jDate - 243 + ly
     ENDIF
   IF jDate > 273 + ly & jDate <= 304 + ly
     ' october
           TheMonth = 10
           TheDay = jDate - 273+ly
     ENDIF
   IF jDate > 304 + ly & jDate <= 334 + ly
     ' november
           TheMonth = 11
           TheDay = jDate - 304 + ly
     ENDIF
   IF jDate > 334 + ly & jDate <= 365 + ly
     ' december
           TheMonth = 12
           TheDay = jDate - 334 + ly
   ENDIF
theDay$ = ltrim$(str$(theDay))
theMonth$ = ltrim$(str$(theMonth))
theYear$ = ltrim$(str$(theYear))
' output can be varied here to suit whatever format you want

IF len(theDay$) = 1 THEN theDay$ = "0"+theDay$
IF len(theMonth$) = 1 THEN theMonth$ = "0"+theMonth$

   IF localsetting = 2
           temp$ = Append$(theDay$,"/",TheMonth$,"/",theYear$)
             retval$ = temp$
   ENDIF
   IF localsetting = 1
           temp$ = Append$(theMonth$,"/",TheDay$,"/",theYear$)
       retval$ = temp$
   ENDIF
LABEL endjDate
RETURN retval$

sub isLeapYear(yyyy:int),int
   retval = yyyy%4 = 0 & yyyy%100 <> 0 | yyyy%400 = 0
return retval


[Sam]

Sam: Good try, but you have to turn your source date into a Julian number, add the days required,
and turn that number back into a readable date. I wish it was that easy!

My bad. In that case you can use the Windows System and File Time API functions. Here's a compilable :

Code Select Expand

$INCLUDE "windowssdk.inc"

  TYPE DateType
     UINT LowDW
     UINT HighDW
  END TYPE

  UNION uDT
     UINT64 qVar
     DateType dtVar
  END UNION

$MAIN

  SYSTEMTIME st
  FILETIME ft
  uDT u
  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)
'Setup the SYSTEMTIME structure with the original date like so:
st.wMonth = 7: st.wDay = 11: st.wYear = 2014
  PRINT USING("Original date = ##/##/####", st.wMonth, st.wDay, 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 * 2) '<---- Add 2 days

  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 USING("##/##/####", st.wMonth, st.wDay, st.wYear)

END



[Sam]

Update:
I've discovered a problem: Don't use the variable qDATE. Instead, use the numbers it was assigned: 24*60*60*10000000. That will work.
Maybe a bug with UINT64 data type. I don't know.

Added: The problem with the quad integer results from the unconventional assignment. If I just assign the number like this  qDATE = 8.64E11, it works fine.
I noticed another compiler didn't like that assignment either. That compiler warned that there would be an integer overflow. I expect that's what happened.
I only wrote it that way to illustrate how a single day is constructed with nanoseconds.
So faith restored in UINT64. 


Sam

[Brian]

Thanks, Sam,

That looks rather nifty! I'll give it a whirl tonight . . .

Brian