Calculations Involving Dates

[Ken Ray]

On 11/19/04 4:59 PM, "Gregory Lypny" <gregory.lypny at videotron.ca> wrote:

> Hello,
> 
> The date format of my Mac is set to Day/Month/Year.   Maybe I've been
> in front of the screen too long, but why does the following handler
> answer No?  Does it mean that the only way to do date calculations is
> with date items?

Here's a handy date math function you can use if you like (comes out of my
STS Code Library in Scripter's Scrapbook):

function stsDateMath pDate1,pOperation,pDate2,pReturnVal
  set the useSystemDate to true
  convert pDate1 to seconds
  if the result is "invalid date" then return "STSError: Invalid Date"
  convert pDate2 to seconds
  if the result is "invalid date" then return "STSError: Invalid Date"
  do "put (" & pDate1 && pOperation && pDate2 & ") into tRetVal"
  if pOperation = "-" then
    switch pReturnVal
    case "days"
      put (tRetVal/86400) into tDays
      return tDays
      break
    case "weeks"
      put ((tRetVal/86400)/7) into tWeeks
      return tWeeks
      break
    case "weeks,days"
      put trunc((tRetVal/86400)/7) into tWeeks
      put ((tRetVal-(tWeeks*7*86400))/86400) into tDays
      return tWeeks,tDays
      break
    end switch
  end if
  return tRetVal
end stsDateMath

This way, you can do this:

  put stsDateMath("9/6/1963", ">", "11/6/1963") --> "TRUE"

Hope this helps,

Ken Ray
Sons of Thunder Software
Web site: http://www.sonsothunder.com/
Email: kray at sonsothunder.com