count vowels

count_vowels.pl

#!/usr/bin/env perl
#
use strict;

my %vowels = (
  a => 0,
  e => 0,
  i => 0,
  o => 0,
  u => 0
);

while(<>) {
  my @chars = split '' ;
  &count_vowels(\%vowels, \@chars);
}
&print_vowel_counts(\%vowels);
&print_most_common_vowel(\%vowels);

### subs
sub print_vowel_counts {
  my $rh_counts = shift;
  my $total = 0;
  foreach my $vowel (sort keys %$rh_counts) {
    print "$vowel => $rh_counts->{$vowel}\n";
    $total += $rh_counts->{$vowel};
  }
  print "\nTotal vowels = $total\n";
}

sub count_vowels {
  my $rh_counts = shift;
  my $rl_chars = shift;

  foreach my $char (@$rl_chars) {
    if (defined $rh_counts->{$char}) {
      $rh_counts->{$char}++;
    }
  }
}

sub print_most_common_vowel  {
  my $rh_vowels = shift;

  my $rh_flipped = &flip_hash($rh_vowels);

  foreach my $count (sort numerically keys %$rh_flipped) {
    print 'Most common vowel'. ($#{$rh_flipped->{$count}} > 0 ? 's' : '') .': '. join(',',@{$rh_flipped->{$count}}) ." ($count)\n";
    last;
  }
}

sub flip_hash {
  my $rh_hash = shift;

  my %new;
  while(my ($k, $v) = each %$rh_hash) {
    push(@{$new{$v}}, $k);
  }
  return \%new;
}

sub numerically { $b <=> $a }