Perl FAQ 4.12
Here's an example of a Julian Date function provided by Thomas R. Kimpton*.
#!/usr/local/bin/perl
@theJulianDate = ( 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334 );
#************************************************************************
#**** Return 1 if we are after the leap day in a leap year. *****
#************************************************************************
sub leapDay
{
my($year,$month,$day) = @_;
if (year % 4) {
return(0);
}
if (!(year % 100)) { # years that are multiples of 100
# are not leap years
if (year % 400) { # unless they are multiples of 400
return(0);
}
}
if (month < 2) {
return(0);
} elsif ((month == 2) && (day < 29)) {
return(0);
} else {
return(1);
}
}
#************************************************************************
#**** Pass in the date, in seconds, of the day you want the *****
#**** julian date for. If your localtime() returns the year day *****
#**** return that, otherwise figure out the julian date. *****
#************************************************************************
sub julianDate
{
my($dateInSeconds) = @_;
my($sec, $min, $hour, $mday, $mon, $year, $wday, $yday);
($sec, $min, $hour, $mday, $mon, $year, $wday, $yday) =
localtime($dateInSeconds);
if (defined($yday)) {
return($yday+1);
} else {
return($theJulianDate[$mon] + $mday + &leapDay($year,$mon,$mday));
}
}
print "Today's julian date is: ",&julianDate(time),"\n";