$NumDays = SubStr(TimeConvert(TimeConvert(first_day_of_next_month) - 86400), 8, 2)

$NumDays = SubStr(TimeConvert(TimeConvert(2007/3/1) - 86400), 8, 2)

;FUNCTION      nCalculateFirstDayOfMonth()      
;
;ACTION        Calculate the first day of any month and year and shows a Calendar
;                   
;PARAMETERS    Set these variables
;              $nMyMonth=6
;              $nMyYear=2007
;              and
;              $nGetFirstDayOfMonth=nCalculateFirstDayOfMonth($nMyMonth,$nMyYear)
; 
;RETURNS       0=Sunday     
;              1=Monday 
;              . 
;              6=Saturday

Break ON

$nMyMonth=6
$nMyYear=2007
$nGetFirstDayOfMonth=nCalculateFirstDayOfMonth($nMyMonth,$nMyYear)
nDisplayCalendar($nGetFirstDayOfMonth,$nMyMonth,$nMyYear) 


Function nCalculateFirstDayOfMonth($nMonth, $nYear)
  Dim $nJan, $nFeb, $nMar, $nApr, $nMay, $nJun, $nJul, $nAug, $nSep, $nOct, $nNov, $nDec, $nCountDays

  ;Days of every month

  $nJan=31
  if $nYear mod 4 = 0
  $nFeb=29
  else
  $nFeb=28	
  endif
  $nMar=31
  $nApr=30
  $nMay=31
  $nJun=30
  $nJul=31
  $nAug=31
  $nSep=30
  $nOct=31
  $nNov=30
  $nDec=31
  
  ;Calculate Number of Days

  $nCountDays= ((($nYear-1)/4)*366)+((($nYear-1)-($nYear-1)/4)*365)
	
  SELECT
  CASE $nMonth=1
       $nCountDays=$nCountDays+1
  CASE $nMonth=2
       $nCountDays=$nCountDays+$nJan+1
  CASE $nMonth=3
       $nCountDays=$nCountDays+$nJan+$nFeb+1
  CASE $nMonth=4
       $nCountDays=$nCountDays+$nJan+$nFeb+$nMar+1
  CASE $nMonth=5
       $nCountDays=$nCountDays+$nJan+$nFeb+$nMar+$nApr+1
  CASE $nMonth=6
       $nCountDays=$nCountDays+$nJan+$nFeb+$nMar+$nApr+$nMay+1
  CASE $nMonth=7
       $nCountDays=$nCountDays+$nJan+$nFeb+$nMar+$nApr+$nMay+$nJun+1
  CASE $nMonth=8
       $nCountDays=$nCountDays+$nJan+$nFeb+$nMar+$nApr+$nMay+$nJun+$nJul+1
  CASE $nMonth=9
       $nCountDays=$nCountDays+$nJan+$nFeb+$nMar+$nApr+$nMay+$nJun+$nJul+$nAug+1
  CASE $nMonth=10
       $nCountDays=$nCountDays+$nJan+$nFeb+$nMar+$nApr+$nMay+$nJun+$nJul+$nAug+$nSep+1
  CASE $nMonth=11
       $nCountDays=$nCountDays+$nJan+$nFeb+$nMar+$nApr+$nMay+$nJun+$nJul+$nAug+$nSep+$nOct+1
  CASE $nMonth=12
       $nCountDays=$nCountDays+$nJan+$nFeb+$nMar+$nApr+$nMay+$nJun+$nJul+$nAug+$nSep+$nOct+$nNov+1
  CASE 1
       ?"Invalid Month"
       EXIT       
  ENDSELECT
  
  ;DETERMINE DAY OF THE WEEK	
  SELECT 
  CASE $nCountDays mod 7 = 0
       $nCalculateFirstDayOfMonth=7
  CASE $nCountDays mod 7 = 1
       $nCalculateFirstDayOfMonth=1
  CASE $nCountDays mod 7 = 2
       $nCalculateFirstDayOfMonth=2
  CASE $nCountDays mod 7 = 3
       $nCalculateFirstDayOfMonth=3
  CASE $nCountDays mod 7 = 4
       $nCalculateFirstDayOfMonth=4
  CASE $nCountDays mod 7 = 5
       $nCalculateFirstDayOfMonth=5
  CASE $nCountDays mod 7 = 6
       $nCalculateFirstDayOfMonth=6
  ENDSELECT

ENDFUNCTION


Function nDisplayCalendar($nFirstDayOfMonth,$nCalendarMonth,$nCalendarYear) 
  dim $nNoOfDaysofMonth, $iRow, $iColomn
  $iRow=6
  CLS

  SELECT
  CASE $nCalendarMonth=1
       $nNoOfDaysOfMonth=31
       at($iRow-4,4) "January of "$nCalendarYear
  CASE $nCalendarMonth=2 and $nCalendarYear mod 4 = 0
       $nNoOfDaysOfMonth=29
       at($iRow-4,4) "February of "$nCalendarYear
  CASE $nCalendarMonth=2 and $nCalendarYear mod 4 <> 0
       $nNoOfDaysOfMonth=28	
       at($iRow-4,4) "February of "$nCalendarYear
  CASE $nCalendarMonth=3
       $nNoOfDaysOfMonth=31
       at($iRow-4,4) "March of "$nCalendarYear
  CASE $nCalendarMonth=4
       $nNoOfDaysOfMonth=30
       at($iRow-4,4) "April of "$nCalendarYear
  CASE $nCalendarMonth=5
       $nNoOfDaysOfMonth=31
       at($iRow-4,4) "May of "$nCalendarYear
  CASE $nCalendarMonth=6
       $nNoOfDaysOfMonth=30
       at($iRow-4,4) "June of "$nCalendarYear
  CASE $nCalendarMonth=7
       $nNoOfDaysOfMonth=31
       at($iRow-4,4) "July of "$nCalendarYear
  CASE $nCalendarMonth=8
       $nNoOfDaysOfMonth=31
       at($iRow-4,4) "August of "$nCalendarYear
  CASE $nCalendarMonth=9
       $nNoOfDaysOfMonth=30
       at($iRow-4,4) "September of "$nCalendarYear
  CASE $nCalendarMonth=10
       $nNoOfDaysOfMonth=31
       at($iRow-4,4) "October of "$nCalendarYear
  CASE $nCalendarMonth=11
       $nNoOfDaysOfMonth=30
       at($iRow-4,4) "November of "$nCalendarYear
  CASE $nCalendarMonth=12
       $nNoOfDaysOfMonth=31
       at($iRow-4,4) "December of "$nCalendarYear
  ENDSELECT
  $iColumn=$nFirstDayOfMonth
  at($iRow-1,4) COLOR w+/b "S   M   T   W   T   F   S " COLOR w+/n     

  for $i=1 to $nNoOfDaysOfMonth  
   at($iRow,$iColumn*4) $i
   if $iColumn mod 7 = 0
   $iRow=$iRow+1
   $iColumn=0
   endif
   $iColumn=$iColumn+1
  next

EndFunction

gets $

; DisplayCalMonth(date)
; Glenn Barnas
; Displays a calendar month, highlighting a specific day
; Accepts a single date argument in the format YYYY/MM/DD
;
Function DisplayCalMonth($_MyDate)

  Dim $_MName					; Array of month names
  Dim $_Offset, $_LOff				; Left offset count, string of spaces
  Dim $_aMyDate					; Array of date values
  Dim $_DCurr, $_DFirst, $_DLast		; Defined day of month, first weekday, last day of month
  Dim $_Header					; header string - Month YYYY
  Dim $_Tag, $_Day				; Loop counter, Day index

  ; Month name array
  $_MName = 'January','February','March','April','May','June','July','August','September','October','November','December'

  ; Left offset is 3 spaces, up to 40 are permitted
  $_Offset = 12
  $_LOff = Left('                                        ', $_Offset)

  ; Split the supplied date value into an array
  $_aMyDate = Split($_MyDate, '/')


  $_dCurr = $_aMyDate[2]			; save the defined day of the month for later reference
  $_aMyDate[2] = '1'				; Change supplied date to reference the first day of the month


  ; Determine first weekday (0=Sunday)
  ; Use TimeConvert to return cTime, divide by seconds/day to determine days, offset by 4 and use mod for a 0-6 DOW value
  $_DFirst = ((TimeConvert(Join($_aMyDate, '/') + ' 00:00:00', 0) / 86400)) Mod 7


  ; Get number of days in the current month - change to first of next month and subtract 1 day
  ; Then get the Day portion. Increment the year if we're in December!
  If Val($_aMyDate[1]) = 12
    $_aMyDate[0] = Val($_aMyDate[0]) + 1
    $_aMyDate[1] = 1
  Else
    $_aMyDate[1] = Val($_aMyDate[1]) + 1
  EndIf


  ; timeConvert date to cTime, subtract 1 day in seconds, and convert back to YYYY/MM/DD format, trim time
  $_DLast = Split(Split(TimeConvert(TimeConvert(Join($_aMyDate, '/') + ' 00:00:00', 0) - 86400, 0), '/')[2], ' ')[0]

  ; Create the header - format is "Month Year" plus an appropriate left offset
  $_Header = $_MName[Val($_aMyDate[1]) - 2] + ' ' + $_aMyDate[0]
  $_Header = Left('                    ', $_Offset + ((28 - Len($_Header)) / 2)) + $_Header


  ; Display the calendar for the defined month, highlighting the specific day
  $_Header ?
  $_LOff COLOR w+/b ' S   M   T   W   T   F   S ' COLOR w+/n

  $_Tag = 0					; loop control
  $_Day = 1					; day value
  While $_Tag >= 0
    If $_Tag <= $_DFirst			; has first day occurred?
      '    '					; if not, print blank entry
    Else
      If $_Day = $_DCurr COLOR y+/r EndIf	; highlight current day
      Right('   ' + CStr($_Day), 3) ' '		; otherwise print formatted day entry
      $_Day = $_Day + 1				; and increment day count
      COLOR w+/n				; restore color
    EndIf

    If $_Tag Mod 7 = 0 @CRLF $_LOff EndIf	; next line, then print offset

    $_Tag = $_Tag + 1
    If $_Day > $_DLast $_Tag = -1 EndIf		; close the loop when we display the last day
  Loop

  ? ?

EndFunction