wordcount.pl - Count Unique Word In Input

This code counts up the instances for each unique word in the input, and prints the words which surpass a given threshold.

#!/usr/bin/perl
use strict;

my ($filename, $threshold, $fh, @word_refs, $word_ref);

($filename, $threshold) = @ARGV;

# Threshold must be an integer
if (!($threshold =~ /^\d+$/)) {
    print "The threshold must be a number.\n";
    exit 1;
}

# Read file and tally word frequencies.
# Original case of word does not matter: "the" = "The" = "THE"
open $fh, "<", $filename;
while (my $line = <$fh>) {
    chomp($line);
    my $found = 0;
    foreach $word_ref (@word_refs) {
        if (lc($word_ref->[0]) eq lc($line)) {
            $found = 1;
            $word_ref->[1]++;
        }
    }

    # initialize a new word with a frequency of 1
    if (not $found) {
        push(@word_refs, [$line, 1]);
    }
}

# Print words and their frequencies, sorted alphabetically by word.  Only
# print a word if its frequency is greater than or equal to the threshold.
foreach $word_ref (sort {lc($a->[0]) cmp lc($b->[0])} @word_refs) {
    next if $word_ref->[1] < $threshold;
    printf "%4d %s\n", $word_ref->[1], $word_ref->[0];
}