open (CORPUS, "little_corpus.txt") or die "Warning! Can't open corpus file 
$!\n";

while ($line = <CORPUS>) {    
    chomp($line);   

    for ($i = 0; $i < length($line); $i++) {
	# The following stores the current character in a "hash table"
	$inventory{substr($line, $i, 1)} = 1 ;
    }
}
# Get a list of all the items in the inventory hash table
@phonemes = keys %inventory;
print "List of all phonemes in the file (" . scalar(@phonemes) . " total)\n";
foreach $phoneme (@phonemes) {
	print "$phoneme "
}
print "\n";

open (TEST, "test_words.txt") or die "Warning! Can't open file of test words: $!\n";
while ($line = <TEST>) {
    chomp($line);
    $legal = 1;        
    for ($i = 0; $i < length($line); $i++) {
	if (not exists $inventory{substr($line, $i, 1)}) {
		print "Word $line is illegal (" . substr($line, $i, 1) ." not in corpus inventory)\n";
		$legal = 0;
		last;		
	}
    }
    if ($legal) {
        print "Word $line is legal\n";        	
    }
}