CalcDayNumber

				But Why? I am writing a Calendar script and I need to allow the user to enter a Date, and display weeks before and after the date. The script I wrote uses localtime() to tell me when the month/year changes as I count off the DayNumber... So, I need to know the starting DayNumber based on the users request.
# USAGE:



 # DD, MM, YYYY

 my $dayNumber = CalcDayNumber( 28, 3,
2003);

# -OR-

 # year value from localtime()

 my $dayNumber = CalcDayNumber( 28, 3,
103);

# -OR-

 # DD, MM, YY

 my $dayNumber = CalcDayNumber( 28, 3,
03);



# NOTE: 

#  Month value is 0 - 11 (not 1-12)

#  These values are those used in localtime()









sub CalcDayNumber { #
$tDaY, $tMon, $tYear

 my ( $tDay, $tMon, $tYear) = @_;

 my $tDayNumber = 0;    # Days
SINCE Jan 1, 1970

 my $tCount;



 # NOTE: since the seconds value tops out 

 #       around 2034, the 100th Year

 #       check for leap year is NOT performed!

 #       ..And since every 1000 years
is a 

 #       leap year 2000 is not effected

 #  ie. this routine is only valid for 

 #       dates between 1/1/1970 - 12/31/2034



 # Fix $tMon ( it might be more than 0-11) 

 # and adjust $tYear

 until( $tMon < scalar( @daysInMonth)) {

  $tMon -= scalar( @daysInMonth);

  $tYear++;

 }



 # default is 4 digit year (2003) ... but



 # allow 2 digit year ( 03)

 $tYear += 100 if( $tYear < 100);



 # allow 3 digit year (from localtime())

 $tYear += 1900 if( $tYear < 1900);



 for( $tCount = 1970; $tCount < $tYear; $tCount++) {

  $tDayNumber += 365;

  $tDayNumber++ unless( $tCount % 4);

 }



 for( $tCount = 0; $tCount < $tMon; $tCount++) {

  $tDayNumber += $daysInMonth[ $tCount];

  # March is effected by leap year

  if( $tCount == 1) {

   $tDayNumber++ unless( $tYear % 4);

  }

 }



 $tDayNumber += $tDay;



 # Returns Days since Jan 1, 1970

 return( $tDayNumber - 1);

} # sub CalcDayNumber