The Levenshtein distance!!!

Must have seen Google responding intelligently to your query like:
Did you mean Google?

How does it does that? Simple, PHP has function called Levenshtein that will do it for you provided you have a collection of words to match against for.

The Levenshtein distance is defined as the minimal number of characters you have to replace, insert or delete to transform str1 into str2 . The complexity of the algorithm is O(m*n), where n and m are the length of str1 and str2 (rather good when compared to similar_text(), which is O(max(n,m)**3), but still expensive).

Try this:

-guess.php

Enter:

// input misspelled word
if(!isset($_GET['q'])) exit();
$input = $_GET['q'];

// array of words to check against
$words = array('apple','pineapple','banana','orange',
'radish','carrot','pea','bean','potato');

// no shortest distance found, yet
$shortest = -1;

// loop through words to find the closest
foreach ($words as $word) {

// calculate the distance between the input word,
// and the current word
$lev = levenshtein($input, $word);

// check for an exact match
if ($lev == 0) {

// closest word is this one (exact match)
$closest = $word;
$shortest = 0;

// break out of the loop; we've found an exact match
break;
}

// if this distance is less than the next found shortest
// distance, OR if a next shortest word has not yet been found
if ($lev <= $shortest || $shortest < 0) {
// set the closest match, and shortest distance
$closest = $word;
$shortest = $lev;
}
}

//echo "Input word: $input\n";
if ($shortest == 0) {
echo "Exact match found: $closest\n";
} else {
echo "Did you mean: $closest?\n";
}

?>
Interesting Is'nt it?
thanks to Code Jockeys community@orkut.