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#!/usr/bin/env perl
# ch-1.pl - Count weekdays (per month) in specified year (or current year)
# Done here with only core modules.
#
# Ryan Thompson <rjt@cpan.org>
use 5.010;
use warnings;
use strict;
use Time::localtime; # Named interface to localtime().
my @Mon = qw< Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec >;
my ( $timestamp, $now ) = ( time, localtime );
my $year = shift // $now->year + 1900; # Year defaults to current year
# Get $timestamp to within correct $year. Almost always loops once.
# Loops twice in edge case with leap years, which is still easier than
# calculating it.
do {
$timestamp += ( $year - ( $now->year + 1900 ) ) * 86400 * 365;
$now = localtime $timestamp;
} while ( $now->year + 1900 != $year );
# Then we just subtract the yday to get our timestamp to yyyy-01-01
$timestamp -= $now->yday * 86400;
$now = localtime $timestamp;
# Now we simply iterate through the year and count up the weekdays.
my %weekdays;
while ( $now->year + 1900 == $year ) {
$weekdays{ $Mon[ $now->mon ] }++ if $now->wday > 0 and $now->wday < 6;
$timestamp += 86400;
$now = localtime $timestamp;
}
say "$_: $weekdays{$_} days" for @Mon;
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