Levenshtein distance 1

levenshtein1.php

<?php

function getLevenshtein1($word)
{
    $words = array();
    for ($i = 0; $i < strlen($word); $i++) {
        // insertions
        $words[] = substr($word, 0, $i) . '_' . substr($word, $i);
        // deletions
        $words[] = substr($word, 0, $i) . substr($word, $i + 1);
        // substitutions
        $words[] = substr($word, 0, $i) . '_' . substr($word, $i + 1);
    }
    // last insertion
    $words[] = $word . '_';
    return $words;
}