How to use the similar_text function to compare similar words

/*
** Function: similar_text (PHP)
** Desc: Shows how to use the similar_text() function to compare similar words.It returns how similar the words are.
** Example: see below
** Author: Jonas John
*/

$word2compare = "stupid";

$words = array(
'stupid',
'stu and pid',
'hello',
'foobar',
'stpid',
'upid',
'stuuupid',
'sstuuupiiid',
);

while(list($id, $str) = each($words))
{
similar_text($str, $word2compare, $percent);

print "Comparing '$word2compare' with '$str': ";
print round($percent) . "%\n";
}

/*
Results:

Comparing 'stupid' with 'stupid': 100%
Comparing 'stupid' with 'stu and pid': 71%
Comparing 'stupid' with 'hello': 0%
Comparing 'stupid' with 'foobar': 0%
Comparing 'stupid' with 'stpid': 91%
Comparing 'stupid' with 'upid': 80%
Comparing 'stupid' with 'stuuupid': 86%
Comparing 'stupid' with 'sstuuupiiid': 71%
*/

?>