I was inspired to write a short Perl script this morning:
#! /usr/bin/perl -w
use strict;
use Time::Local;
# Restrict years to the Unix epoch
my $start_year = 1970;
my $end_year = 2037;
my $count = 0;
my $year;
my $month;
my @mon = qw( Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec );
sub try_month {
my $month = shift;
my $year = shift() - 1900;
my $time = timelocal( 0, 0, 1, 13, $month, $year );
my @test = localtime( $time );
# Is the 13th on a Friday?
if( $test[6] == 5 ) {
print "$mon[$month] ";
$count++;
}
} # end try_month
for( $year = $start_year; $year <= $end_year; $year++ ) {
print "$year ";
for( $month = 0; $month < 12; $month++ ) {
try_month( $month, $year );
}
print "\n";
}
print "Total $count\n";
Today is the second Friday the 13th of three that will occur this year.
What I learned from running this script:
- Every year has at least one Friday the 13th
- Friday the 13th can occur in any month of the year
- When there are three '13ths' in a year they either occur in
February/March/November or January/April/July
- Jan/Apr/Jul '13ths' only happen in a leap year and Feb/Mar/Nov only
happen in non leap years
Curt
--
You received this message because you are subscribed to the Google Groups
"NLUG" group.
To post to this group, send email to [email protected]
To unsubscribe from this group, send email to
[email protected]
For more options, visit this group at
http://groups.google.com/group/nlug-talk?hl=en
