check if an item is a date

Rob Cozens rcozens at pon.net
Thu Mar 17 10:59:27 EST 2005


This is nothing new, Xavier,

>But surprise!
>
>put (2485694 is a date)
>
>It gets worse... 1 is also a date!
>
>So either the << is a date>> function is useless as a date checker and we
>all must roll our own AGAIN

Virtually any integer represents a date in seconds format in xTalks; so if 
you need need to validate an input string as a valid date (as per system 
date format), you need more:

 From Serendipity Library <http://wecode.org/serendipity/>:

function validDate theString -- 5 April 04:RCC
   put stripBlanks(theString,false) into theString
   get systemDateFormat()
   set the itemDelimiter to char -1 of it -- theSeparator
   if the number of items of theString <> 3 then return false
   delete the last char of it
   delete char offset("mm",it) of it -- remove double characters, if any
   delete char offset("dd",it) of it
   delete char offset("yy",it) of it
   repeat with x = 1 to 3
     switch char x of it
     case "m"
       put item x of theString into theMonth
       if not validDigits(theMonth) then return false
       if theMonth < 1 or theMonth > 12 then return false
       break
     case "d"
       put item x of theString into theDay
       if not validDigits(theDay) then return false
       if theDay < 1 or theDay > 31 then return false
       break
     case "y"
       put item x of theString into theYear
       if not validDigits(theYear) then return false
       put length(theYear) into charCount
       if charCount <> 2 and charCount <> 4 then return false
       if charCount is 2 then add 2000 to theYear
       if theYear < 1 then return false
       break
     end switch
   end repeat
   if theDay < 29 then return 
true&return&theYear&comma&theMonth&comma&theDay&",0,0,0,0"
   if theMonth is 2 then
     if theDay > 29 or not leapYear(theYear) then return false
     else return true&return&theYear&comma&theMonth&comma&theDay&",0,0,0,0"
   else
     if offset("0",theMonth) = 1 then delete char 1 of theMonth
     set the itemDelimiter to comma
     if theMonth is among the items of "1,3,5,7,8,10,12" then return 
true&return&theYear&comma&theMonth&comma&theDay&",0,0,0,0"
     if theDay is 31 then return false
     else return true&return&theYear&comma&theMonth&comma&theDay&",0,0,0,0"
   end if
end validDate

Note this uses the systemDateFormat function I posted yesterday, plus other 
Library handlers.

Rob Cozens CCW
Serendipity Software Company

"And I, which was two fooles, do so grow three;
  Who are a little wise, the best fooles bee."

  from "The Triple Foole" by John Donne (1572-1631) 



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