Arrays and functions: The current script

#!/usr/bin/perl
#Search for songs in a file of the following tab-separated data:
# title, duration, artist, album, year, rating, rip date, track position, genre

#options for the --format switch
@validFormats = ("raw", "simple", "html", "summary");
$validFormats = englishJoin(", ", "or", @validFormats);

#strip off the command-line switches and act on or remember them
while ($ARGV[0] =~ /^--(.+)/) {
$switch = $1;

#pull this switch off of the front of the list
shift;

#if they ask for help, do it and exit
if ($switch eq "help") {
help();
exit;
} elsif ($switch eq "case") {
$sensitive = 1;
} elsif ($switch eq "reverse") {
$reverse = 1;
} elsif ($switch eq "limit") {
$limit = shift;
if ($limit !~ /^[1-9][0-9]*$/) {
print "\nYou must limit to a number, such as '33' or '2'.\n\n";
help();
exit;
}
} elsif ($switch eq "format") {
$format = shift;
if (!grep(/^$format$/, @validFormats)) {
print "\nFormat must be $validFormats.\n\n";
help();
exit;
}
} else {
print "\nI do not understand the option '$switch'.\n\n";
help();
exit;
}
}

#the first item on the command line is what we're searching for
if ($searchFor = shift) {
while (<>) {
#split out the song, duration, artist, and album
($song, $duration, $artist, $album) = split("\t");

if ($sensitive) {
$matched = /$searchFor/;
} else {
$matched = /$searchFor/i;
}

#reverse the match if we want non-matching lines
if ($reverse) {
$matched = !$matched;
}

#print the information if this line is one we want
if ($matched) {
$matches++;
if ($format eq "raw") {
print;
} elsif ($format eq "html") {
print "<tr><td>$song</td><td>$album</td><td>$artist</td></tr>\n";
} elsif ($format eq "summary") {
$artists{$artist}++;
} else {
print "$song ($album, by $artist)\n";
}
}
last if $limit && $matches >= $limit;
}

if (%artists) {
@artists = keys %artists;
@artists = sort byArtistCount @artists;
foreach $artist (@artists) {
$artistCount = $artists{$artist};
print "$artist: $artistCount\n";
}
}
} else {
help();
}

#describe how this script is used
sub help {
print "Syntax: show <search text> [song files]\n";
print "\tSearch for <search text> in the song file. If no song file is specified\n";
print "\t'show' will expect it on standard input.\n";
print "\tA song file is a tab-delimited file with:\n";
print "\ttitle, duration, artist, album, year, rating, rip date, track position, genre\n";
print "\t--help: print this help text\n";
print "\t--case: be sensitive to upper and lower case\n";
print "\t--reverse: filter out songs that contain the search text\n";
print "\t--limit x: limit to x results\n";
print "\t--format <$validFormats>: choose format for results\n";
}

sub byArtistCount {
return $artists{$b} <=> $artists{$a};
}

sub englishJoin {
my($punctuation) = shift;
my($conjunction) = shift;
my(@items) = @_;

my($joined, $finalItem);

if ($#items == -1) {
$joined = "";
} elsif ($#items == 0) {
$joined = $items[0];
} elsif ($#items == 1) {
$joined = join(" $conjunction ", @items);
} else {
$finalItem = pop(@items);
$joined = join($punctuation, @items) . "$punctuation$conjunction $finalItem";
}

return $joined;
}