Agility Kata "Word Count VIII"

Optionally, the text can be compared with a dictionary of known words. When the index is printed, it marks words not found in the dictionary with an asterisk and indicates the number of unknown words, e.g.

$ wordcount -index -dictionary=dict.txt
Enter text: Mary had a little lamb
Number of words: 4, unique: 4; average word length: 4.25 characters
Index (unknown: 2):
had
lamb*
little
Mary*
$

The file dict.txt looks as follows:

big
small
little
cat
dog
have
has
had