PHP Simple Spell Checker (Binary Search help) - php

Question

I need help with performing a binary search with a search term ($searchTerm) and comparing it to a dictionary ($dictionary).
Basically, it reads a dictionary file into an array. The user inputs some words, that string becomes $checkMe. I do an explode function and it turns into $explodedCheckMe. I pass each term in $checkMe to binarySearch as $searchTerm (Okay, my code is confusing). I think my logic is sound, but my syntax isn't ...
I've been using this a lot: http://us3.php.net/manual/en/function.strcasecmp.php
here is my code: paste2.org/p/457232

Answer 1

I know this doesn't directly answer your question, but have you considered using pspell and a custom dictionary?

Answer 2

So you are looking up exact strings in the dictionary. Why don't you a simple array for this? The native PHP's hash table is definitely going to be faster than a binary search implemented in PHP.
while (!feof($file)) {
$dictionary[strtolower(fgets($file))] = 1;
}
...
function search($searchTerm, $dictionary) {
if ($dictionary[strtolower($searchTerm)]) {
// do something
}
}
But if you really want to use a binary search, try this:
function binarySearch($searchTerm, $dictionary) {
$minVal = 0;
$maxVal = count($dictionary);
while ($minVal < $maxVal) {
$guess = intval($minVal + ($maxVal - $minVal) / 2);
$result = strcasecmp($dictionary[$guess], $searchTerm);
if ($result == 0) {
echo "FOUND";
return;
}
elseif ($result < 0) {
$minVal = $guess + 1;
}
else {
$maxVal = $guess;
}
}
}
The main problem was that you can't set $maxval to $guess - 1. See the wikipedia article on binary search, it's really good.